Delayed Sleep Phase Syndrome

Complex MONDO:0024377 Pathograph 3 Circadian Rhythm Sleep Disorder Sleep Disorder

Delayed sleep phase syndrome (DSPS), also known as delayed sleep-wake phase disorder (DSWPD), is a circadian rhythm sleep disorder characterized by a persistent and significant delay of the major sleep episode relative to the desired clock time. Affected individuals typically cannot fall asleep until well past midnight (often 2-6 AM) and, if unrestricted, sleep normally in duration and quality but at a delayed schedule. When forced to adhere to conventional schedules, patients experience chronic sleep deprivation, excessive daytime sleepiness, and difficulty with morning awakening. The disorder has a strong genetic component involving circadian clock genes, with onset predominantly in adolescence. A familial form caused by gain-of-function CRY1 mutations follows autosomal dominant inheritance.

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2
Inheritance
3
Pathophys.
6
Phenotypes
3
Pathograph
3
Genes
5
Treatments
2
Subtypes
2
Trials
1
Deep Research
🏷

Classifications

Harrison's Chapter
NEUROLOGIC
👪

Inheritance

2
Complex/Multifactorial
Show evidence (1 reference)
PMID:28388406 SUPPORT Human Clinical
"many classical twin studies have found a strong hereditary component to chronotype preference in the range of 40–50%, arguing for an important role of genetic predisposition to DSPD etiology"
Twin studies demonstrate 40-50% heritability of chronotype preference, supporting a significant genetic contribution to DSPS susceptibility.
Autosomal dominant (CRY1 subtype)
Show evidence (1 reference)
PMID:28388406 SUPPORT Human Clinical
"Delayed sleep behavior was found to be common among male and female family members and across several generations, consistent with an autosomal dominant inheritance pattern"
Demonstrates autosomal dominant inheritance of CRY1-related DSPD across multiple generations in affected families.
◆

Subtypes

2
Circadian-Delayed DSWPD
~60%
The majority subtype (~60% of cases) characterized by objectively delayed circadian phase markers, including delayed dim light melatonin onset (DLMO) and core body temperature minimum. These patients have a true delay of the endogenous circadian pacemaker relative to the light-dark cycle.
Show evidence (1 reference)
PMID:37275982 SUPPORT Human Clinical
"individuals with DSWPD without having misalignment of objectively measured circadian rhythm markers account for approximately 40% of the cases, wherein the psychological and behavioral characteristics of young people, such as truancy and academic or social troubles, are largely involved in the..."
By stating that ~40% of DSWPD cases have normal circadian markers, this implies ~60% have delayed circadian markers, defining the circadian-delayed subtype.
Circadian-Entrained DSWPD
~40%
A substantial subtype (~40% of cases) in which patients present with clinically delayed sleep timing despite normal objective circadian rhythm markers (e.g., normal DLMO timing). Psychological and behavioral factors, including academic/social difficulties, are more prominently involved in the mechanism of delayed sleep in this subgroup.
Show evidence (1 reference)
PMID:37275982 SUPPORT Human Clinical
"individuals with DSWPD without having misalignment of objectively measured circadian rhythm markers account for approximately 40% of the cases, wherein the psychological and behavioral characteristics of young people, such as truancy and academic or social troubles, are largely involved in the..."
Directly describes the circadian-entrained subtype, accounting for ~40% of DSWPD cases with normal melatonin timing but behaviorally delayed sleep schedules.
⚙

Pathophysiology

3
Circadian Clock Gene Polymorphisms
Variants in core circadian clock genes alter the molecular oscillator that drives the sleep-wake cycle. The circadian clock operates via transcription- translation feedback loops involving CLOCK, BMAL1, PER, and CRY gene families. A gain-of-function mutation in CRY1 (c.1657+3A>C) creates a transcriptional inhibitor with enhanced affinity for Clock and Bmal1, lengthening the circadian period by approximately 30 minutes. Additional polymorphisms in PER3 and CLOCK contribute to DSPS susceptibility.
Neuron link
CRY1 link PER3 link CLOCK link
Circadian Rhythm link
Show evidence (3 references)
PMID:28388406 SUPPORT Human Clinical
"we report a hereditary form of DSPD associated with a dominant coding variation in the core circadian clock gene CRY1, which creates a transcriptional inhibitor with enhanced affinity for circadian activator proteins Clock and Bmal1. This gain-of-function CRY1 variant causes reduced expression..."
This landmark Cell paper establishes CRY1 as a causative gene for familial DSPD, demonstrating a gain-of-function mechanism that lengthens the circadian period and delays sleep phase.
PMID:12841365 SUPPORT Human Clinical
"The Per3 polymorphism correlated significantly with extreme diurnal preference, the longer allele associating with morningness and the shorter allele with eveningness. The shorter allele was strongly associated with the delayed sleep phase syndrome patients, 75% of whom were homozygous."
Demonstrates the PER3 VNTR polymorphism as a genetic marker for DSPS, with the shorter 4-repeat allele associated with evening preference and DSPS.
PMID:36028773 SUPPORT Human Clinical
"Circadian rhythms and sleep are fundamental biological processes integral to human health. Their disruption is associated with detrimental physiological consequences, including cognitive, metabolic, cardiovascular and immunological dysfunctions."
This Nature Reviews Genetics review summarizes the genetic architecture of circadian and sleep traits, including Mendelian forms of delayed sleep-wake phase disorder linked to clock genes.
Altered Melatonin Secretion Timing
DSPS patients exhibit a delayed dim light melatonin onset (DLMO), reflecting a shifted circadian pacemaker. The suprachiasmatic nucleus (SCN) signal to the pineal gland for melatonin synthesis is phase-delayed, resulting in later endogenous melatonin rise and consequently delayed sleep propensity. This delay in melatonin secretion is a hallmark biomarker of the condition. However, approximately 40% of DSWPD cases may have normal melatonin timing, suggesting heterogeneity in the underlying mechanism.
Pinealocyte link
Melatonin Biosynthetic Process link
Show evidence (2 references)
PMID:37275982 SUPPORT Human Clinical
"individuals with DSWPD without having misalignment of objectively measured circadian rhythm markers account for approximately 40% of the cases, wherein the psychological and behavioral characteristics of young people, such as truancy and academic or social troubles, are largely involved in the..."
Demonstrates that DSWPD is heterogeneous with respect to melatonin timing, with approximately 40% of cases showing normal circadian rhythm markers despite delayed sleep schedules, suggesting both circadian-delayed and circadian-entrained subtypes.
PMID:28388406 SUPPORT Human Clinical
"Consistent with a phase delay, entrained DLMO occurred at 2:32 am, well after the time expected in a subject of normal chronotype (typically between 8 to 10 pm) and closer to the time of habitual sleep onset"
Demonstrates objectively measured delayed DLMO (2:32 AM vs. normal 8-10 PM) in a DSPD proband, confirming delayed melatonin secretion as a marker of circadian phase delay.
Impaired Photic Entrainment
The circadian system normally entrains to the 24-hour light-dark cycle through retinal light input to the SCN via melanopsin-containing intrinsically photosensitive retinal ganglion cells (ipRGCs). In DSPS, there may be increased sensitivity to the melatonin-suppressing effect of evening light, and potentially impaired melanopsin-dependent phototransduction, resulting in a net phase delay of the circadian oscillator.
Retinal Ganglion Cell link
Entrainment of Circadian Clock link
Show evidence (1 reference)
PMID:28388406 SUPPORT Human Clinical
"The pathophysiology of DSPD remains obscure with suspected causes including a differential susceptibility of an individual's circadian clock to environmental entrainment cues such as the light/dark cycle, and altered properties of the oscillator itself that affect its period length"
Identifies altered light entrainment susceptibility as a suspected pathophysiological mechanism in DSPD, alongside intrinsic oscillator changes.
⬡

Pathograph

Use the checkboxes to hide or show graph categories. Hover nodes for evidence and cross-linked metadata.
Pathograph: causal mechanism network for Delayed Sleep Phase Syndrome Interactive directed graph showing how pathophysiology mechanisms, phenotypes, genetic factors and variants, experimental models, environmental triggers, and treatments relate through causal and linked edges.
●

Phenotypes

6
Endocrine 1
Abnormal Pineal Melatonin Secretion FREQUENT Abnormal pineal melatonin secretion (HP:0012689)
Show evidence (1 reference)
PMID:28388406 SUPPORT Human Clinical
"Consistent with a phase delay, entrained DLMO occurred at 2:32 am, well after the time expected in a subject of normal chronotype (typically between 8 to 10 pm) and closer to the time of habitual sleep onset"
Documents a markedly delayed DLMO in a DSPD patient, occurring at 2:32 AM compared to the normal 8-10 PM range.
Nervous System 5
Sleep Onset Insomnia VERY_FREQUENT Sleep onset insomnia (HP:0031354)
Show evidence (1 reference)
PMID:37275982 SUPPORT Human Clinical
"Delayed sleep-wake phase disorder (DSWPD) is a sleep disorder in which the habitual sleep-wake timing is delayed, resulting in difficulty in falling asleep and waking up at the desired time."
Confirms that difficulty falling asleep at desired times is a defining feature of DSWPD.
Excessive Daytime Sleepiness VERY_FREQUENT Drowsiness (HP:0002329)
Show evidence (1 reference)
PMID:37275982 SUPPORT Human Clinical
"Patients with DSWPD frequently experience fatigue, impaired concentration, sleep deprivation during weekdays, and problems of absenteeism, which may be further complicated by depressive symptoms."
Documents fatigue, impaired concentration, and sleep deprivation as frequent consequences of DSWPD when patients must adhere to conventional schedules.
Sleep-Wake Cycle Disturbance VERY_FREQUENT Sleep-wake cycle disturbance (HP:0006979)
Show evidence (1 reference)
PMID:28388406 SUPPORT Human Clinical
"Delayed Sleep Phase Disorder (DSPD), which is characterized by a persistent and intractable delay of sleep onset and offset times relative to the societal norm, represents the most commonly diagnosed type of circadian rhythm sleep disorder"
Confirms persistent delay of both sleep onset and offset times as the defining characteristic of DSPD, reflecting a shifted sleep-wake cycle.
Depression FREQUENT Depression (HP:0000716)
Depression is frequently comorbid with DSPS rather than a core phenotype. It may be driven by chronic sleep deprivation, circadian misalignment, and/or shared genetic factors (CRY1 variant carriers show phenome-wide associations with major depressive disorder). Retained as a phenotype because the bidirectional relationship and high frequency in DSWPD populations make it clinically relevant.
Show evidence (2 references)
PMID:37275982 SUPPORT Human Clinical
"DSWPD is frequently comorbid with psychiatric disorders, particularly mood and neurodevelopmental disorders, both of which have a bidirectional association with the pathophysiology of DSWPD."
Establishes frequent comorbidity between DSWPD and mood disorders, with a bidirectional pathophysiological relationship.
PMID:32538895 SUPPORT Human Clinical
"we found in a phenome-wide association study involving 9438 unrelated adult Europeans that CRY1Δ11 was associated with major depressive disorder, insomnia, and anxiety."
Phenome-wide association study demonstrates that the CRY1 DSPD variant is associated with major depressive disorder, providing a genetic link between circadian disruption and depression.
Anxiety FREQUENT Anxiety (HP:0000739)
Show evidence (2 references)
PMID:37275982 SUPPORT Human Clinical
"patients with DSWPD have a strong tendency toward neuroticism and anxiety, which may result in the aggravation of insomnia symptoms."
Documents the strong association between DSWPD and anxiety traits.
PMID:32538895 SUPPORT Human Clinical
"we found in a phenome-wide association study involving 9438 unrelated adult Europeans that CRY1Δ11 was associated with major depressive disorder, insomnia, and anxiety."
Phenome-wide association study links the CRY1 DSPD variant to anxiety.
🧬

Genetic Associations

3
CRY1 (Causative)
Autosomal dominant
Show evidence (2 references)
PMID:28388406 SUPPORT Human Clinical
"we report a hereditary form of DSPD associated with a dominant coding variation in the core circadian clock gene CRY1, which creates a transcriptional inhibitor with enhanced affinity for circadian activator proteins Clock and Bmal1. This gain-of-function CRY1 variant causes reduced expression..."
Landmark study identifying CRY1 c.1657+3A>C as a gain-of-function variant causing familial DSPD with autosomal dominant inheritance and up to 0.6% allele frequency.
PMID:32538895 SUPPORT Human Clinical
"One variant, CRY1Δ11 c.1657+3A>C, is present in approximately 1% of Europeans, therefore standing out as a diagnostic and therapeutic marker. We showed by exome sequencing in an independent cohort of patients with combined ADHD and insomnia that 8 of 62 patients and 0 of 369 controls carried CRY1Δ11."
Validates CRY1Δ11 as a common variant (~1% in Europeans) enriched in patients with ADHD and insomnia, confirming its role in delayed sleep phase phenotypes.
PER3 (Risk Factor)
Show evidence (1 reference)
PMID:12841365 SUPPORT Human Clinical
"The Per3 polymorphism correlated significantly with extreme diurnal preference, the longer allele associating with morningness and the shorter allele with eveningness. The shorter allele was strongly associated with the delayed sleep phase syndrome patients, 75% of whom were homozygous."
Establishes the PER3 VNTR polymorphism as a genetic marker for DSPS, with the shorter 4-repeat allele strongly associated with DSPS patients.
PER2 (Risk Factor)
Show evidence (1 reference)
PMID:31527662 SUPPORT Human Clinical
"A low-frequency missense variant (p.Val1205Met) in PER2 showed a significant association with DSWPD (2.5% in cases and 1.1% in controls, P = 0.026, odds ratio (OR) = 2.32)."
Case-control genetic association data support PER2 p.Val1205Met as a DSWPD risk variant in a Japanese population.
💊

Treatments

5
Strategically Timed Melatonin
Action: melatonin supplementation Ontology label: Pharmacotherapy NCIT:C15986
Low-dose melatonin (0.5-5 mg) administered in the evening, typically 3-7 hours before desired sleep onset (relative to DLMO), to phase-advance the circadian clock. Dosing time relative to DLMO is more critical than dose variation for phase shifting.
Show evidence (1 reference)
PMID:26414986 SUPPORT Human Clinical
"Available data allowed for positive endorsement (at a second-tier degree of confidence) of strategically timed melatonin (for the treatment of DSWPD, blind adults with N24SWD, and children/adolescents with ISWRD and comorbid neurological disorders), and light therapy with or without accompanying..."
AASM Clinical Practice Guideline provides second-tier endorsement for strategically timed melatonin in DSWPD treatment.
Bright Light Therapy
Timed exposure to bright light (2,500-10,000 lux) in the morning, timed after the core body temperature minimum or 1-3 hours before spontaneous awakening, to phase-advance the circadian clock. The AASM guideline endorses light therapy for children and adolescents with DSWPD.
Show evidence (1 reference)
PMID:26414986 SUPPORT Human Clinical
"Available data allowed for positive endorsement (at a second-tier degree of confidence) of strategically timed melatonin (for the treatment of DSWPD, blind adults with N24SWD, and children/adolescents with ISWRD and comorbid neurological disorders), and light therapy with or without accompanying..."
AASM Clinical Practice Guideline provides second-tier endorsement for light therapy with or without behavioral interventions specifically for children and adolescents with DSWPD; adult DSWPD was not endorsed for light therapy in this guideline.
Chronotherapy
Progressive delay of sleep times around the clock until the desired bedtime is reached. This approach exploits the natural tendency toward phase delay but requires strict schedule adherence and is difficult to maintain long-term.
Show evidence (1 reference)
PMID:26414986 NO_EVIDENCE Human Clinical
"No recommendations were provided for remaining treatments/ populations, due to either insufficient or absent data."
The AASM guideline could not provide recommendations for chronotherapy in DSWPD due to insufficient evidence, reflecting the limited data supporting this approach.
Tasimelteon
Action: tasimelteon Ontology label: Pharmacotherapy NCIT:C15986
A dual MT1/MT2 melatonin receptor agonist under investigation for DSWPD. Clinical trials include evaluation in the general DSWPD population and in CRY1Δ11 variant carriers specifically. A case report describes symptom resolution in a DSWPD patient treated with tasimelteon.
Show evidence (1 reference)
DOI:10.3389/fnins.2023.1287514 SUPPORT Human Clinical
"The participant was enrolled in an 11-month Open-Label Extension (OLE) following the randomized portion of a clinical study and was successfully treated with tasimelteon. DSWPD symptoms were resolved, and their previously delayed sleep-wake cycle was advanced."
Case report demonstrating successful resolution of DSWPD symptoms with tasimelteon treatment, with advancement of the previously delayed sleep-wake cycle. Note: this patient had comorbid Optic Nerve Hypoplasia (ONH), which commonly impairs photic entrainment and can independently cause non-24-hour sleep-wake disorder; this comorbidity limits generalizability to uncomplicated DSWPD.
Cognitive-Behavioral Interventions
Action: cognitive and behavioral intervention MAXO:0000010
Behavioral approaches including sleep hygiene education, stimulus control, and cognitive therapy for insomnia-related cognitions. Particularly relevant for the circadian-entrained DSWPD subtype where psychological and behavioral factors play a larger role.
Show evidence (1 reference)
PMID:37275982 SUPPORT Human Clinical
"future studies should address the effectiveness of cognitive-behavioral approaches in addition to chronobiological approaches in the treatment of DSWPD."
Highlights the need for cognitive-behavioral interventions as adjuncts to chronobiological treatments, particularly given the circadian-entrained subtype where behavioral factors predominate.
🌍

Environmental Factors

2
Evening and Nighttime Light Exposure
Exposure to artificial light, particularly short-wavelength (blue, ~480 nm) light from screens and indoor lighting during evening hours, suppresses melatonin secretion and exacerbates circadian phase delay. DSWPD patients may have higher photosensitivity to evening light compared to normal sleepers, amplifying the phase-delaying effect. The COVID-19 pandemic period demonstrated that behavioral changes in light exposure and schedule patterns can promote delayed sleep phase.
Show evidence (2 references)
PMID:28388406 SUPPORT Human Clinical
"The pathophysiology of DSPD remains obscure with suspected causes including a differential susceptibility of an individual's circadian clock to environmental entrainment cues such as the light/dark cycle, and altered properties of the oscillator itself that affect its period length"
Identifies differential susceptibility to the light/dark cycle as a suspected environmental contributor to DSPD pathophysiology.
PMID:37275982 SUPPORT Human Clinical
"delayed sleep phase and prolonged sleep duration in the young generation have been reported during the period of COVID-19 pandemic-related behavioral restrictions. This phenomenon raises a concern about the risk of a mismatch between their sleep-wake phase and social life that may lead to the..."
Documents that behavioral restrictions (including altered light exposure patterns and schedules) during the pandemic promoted delayed sleep phase, supporting environmental contributions to DSWPD development.
Social Jet Lag and Schedule Misalignment
Mismatch between the individual's endogenous circadian phase and social obligations (school, work schedules) exacerbates symptoms and perpetuates the delayed phase. Adolescents and young adults are particularly vulnerable due to developmental changes in circadian timing that coincide with early school start times.
Show evidence (1 reference)
PMID:37275982 SUPPORT Human Clinical
"DSWPD is typically prevalent during adolescence and young adulthood."
Documents the high prevalence of DSWPD in adolescents and young adults, consistent with developmental circadian changes interacting with social schedule demands.
🔬

Clinical Trials

2
NCT04652882 PHASE_III COMPLETED
A multicenter, double-blind, randomized study evaluating the efficacy and safety of daily oral tasimelteon versus placebo in participants with DSWPD.
Show evidence (1 reference)
clinicaltrials:NCT04652882 SUPPORT
"This is a multicenter, double-blind, randomized study to evaluate the efficacy and safety of a daily single oral dose of tasimelteon and matching placebo in male and female participants with DSWPD."
Phase III trial directly evaluating tasimelteon for DSWPD, the most common circadian rhythm sleep disorder.
NCT06701396 PHASE_III RECRUITING
A double-blind, randomized, two-period crossover study evaluating tasimelteon versus placebo specifically in patients with DSWPD who carry the CRY1Δ11 variant. This precision medicine trial targets the genetically defined DSWPD subtype.
Show evidence (1 reference)
clinicaltrials:NCT06701396 SUPPORT
"This is a double-blind, randomized, two-period crossover study to evaluate the efficacy and safety of a single oral dose of tasimelteon and matching placebo in male and female subjects with DSWPD and the CRY1Δ11 variant."
First precision medicine trial in DSWPD, targeting patients with the CRY1Δ11 genetic variant for tasimelteon treatment.
{ }

Source YAML

click to show 
name: Delayed Sleep Phase Syndrome
creation_date: "2026-02-26T12:00:00Z"
updated_date: "2026-03-08T16:46:46Z"
category: Complex
categories:
- Sleep Disorder
- Circadian Rhythm Sleep-Wake Disorder
- Circadian Timing Disorder
parents:
- Circadian Rhythm Sleep Disorder
- Sleep Disorder
disease_term:
  preferred_term: Delayed Sleep Phase Syndrome
  term:
    id: MONDO:0024377
    label: circadian rhythm sleep disorder, delayed sleep phase type
description: >-
  Delayed sleep phase syndrome (DSPS), also known as delayed sleep-wake phase
  disorder (DSWPD), is a circadian rhythm sleep disorder characterized by a
  persistent and significant delay of the major sleep episode relative to the
  desired clock time. Affected individuals typically cannot fall asleep until
  well past midnight (often 2-6 AM) and, if unrestricted, sleep normally in
  duration and quality but at a delayed schedule. When forced to adhere to
  conventional schedules, patients experience chronic sleep deprivation, excessive
  daytime sleepiness, and difficulty with morning awakening. The disorder has a
  strong genetic component involving circadian clock genes, with onset
  predominantly in adolescence. A familial form caused by gain-of-function
  CRY1 mutations follows autosomal dominant inheritance.
has_subtypes:
- name: Circadian-Delayed DSWPD
  description: >-
    The majority subtype (~60% of cases) characterized by objectively delayed
    circadian phase markers, including delayed dim light melatonin onset (DLMO)
    and core body temperature minimum. These patients have a true delay of the
    endogenous circadian pacemaker relative to the light-dark cycle.
  subtype_frequency: "~60%"
  classification: clinical_phenotype
  evidence:
  - reference: PMID:37275982
    reference_title: "Delayed sleep-wake phase disorder and its related sleep behaviors in the young generation."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      individuals with DSWPD without having misalignment of objectively measured
      circadian rhythm markers account for approximately 40% of the cases,
      wherein the psychological and behavioral characteristics of young people,
      such as truancy and academic or social troubles, are largely involved in
      the mechanism of this disorder.
    explanation: >-
      By stating that ~40% of DSWPD cases have normal circadian markers, this
      implies ~60% have delayed circadian markers, defining the circadian-delayed
      subtype.
- name: Circadian-Entrained DSWPD
  description: >-
    A substantial subtype (~40% of cases) in which patients present with
    clinically delayed sleep timing despite normal objective circadian rhythm
    markers (e.g., normal DLMO timing). Psychological and behavioral factors,
    including academic/social difficulties, are more prominently involved in
    the mechanism of delayed sleep in this subgroup.
  subtype_frequency: "~40%"
  classification: clinical_phenotype
  evidence:
  - reference: PMID:37275982
    reference_title: "Delayed sleep-wake phase disorder and its related sleep behaviors in the young generation."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      individuals with DSWPD without having misalignment of objectively measured
      circadian rhythm markers account for approximately 40% of the cases,
      wherein the psychological and behavioral characteristics of young people,
      such as truancy and academic or social troubles, are largely involved in
      the mechanism of this disorder.
    explanation: >-
      Directly describes the circadian-entrained subtype, accounting for ~40%
      of DSWPD cases with normal melatonin timing but behaviorally delayed
      sleep schedules.
pathophysiology:
- name: Circadian Clock Gene Polymorphisms
  description: >-
    Variants in core circadian clock genes alter the molecular oscillator that
    drives the sleep-wake cycle. The circadian clock operates via transcription-
    translation feedback loops involving CLOCK, BMAL1, PER, and CRY gene
    families. A gain-of-function mutation in CRY1 (c.1657+3A>C) creates a
    transcriptional inhibitor with enhanced affinity for Clock and Bmal1,
    lengthening the circadian period by approximately 30 minutes. Additional
    polymorphisms in PER3 and CLOCK contribute to DSPS susceptibility.
  cell_types:
  - preferred_term: Neuron
    term:
      id: CL:0000540
      label: neuron
  biological_processes:
  - preferred_term: Circadian Rhythm
    term:
      id: GO:0007623
      label: circadian rhythm
  genes:
  - preferred_term: CRY1
    term:
      id: hgnc:2384
      label: CRY1
  - preferred_term: PER3
    term:
      id: hgnc:8847
      label: PER3
  - preferred_term: CLOCK
    term:
      id: hgnc:2082
      label: CLOCK
  evidence:
  - reference: PMID:28388406
    reference_title: "Mutation of the Human Circadian Clock Gene CRY1 in Familial Delayed Sleep Phase Disorder."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      we report a hereditary form of DSPD associated with a dominant coding
      variation in the core circadian clock gene CRY1, which creates a
      transcriptional inhibitor with enhanced affinity for circadian activator
      proteins Clock and Bmal1. This gain-of-function CRY1 variant causes
      reduced expression of key transcriptional targets and lengthens the period
      of circadian molecular rhythms, providing a mechanistic link to DSPD
      symptoms.
    explanation: >-
      This landmark Cell paper establishes CRY1 as a causative gene for familial
      DSPD, demonstrating a gain-of-function mechanism that lengthens the
      circadian period and delays sleep phase.
  - reference: PMID:12841365
    reference_title: "A length polymorphism in the circadian clock gene Per3 is linked to delayed sleep phase syndrome and extreme diurnal preference."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The Per3 polymorphism correlated significantly with extreme diurnal
      preference, the longer allele associating with morningness and the shorter
      allele with eveningness. The shorter allele was strongly associated with
      the delayed sleep phase syndrome patients, 75% of whom were homozygous.
    explanation: >-
      Demonstrates the PER3 VNTR polymorphism as a genetic marker for DSPS,
      with the shorter 4-repeat allele associated with evening preference
      and DSPS.
  - reference: PMID:36028773
    reference_title: "Genetics of circadian rhythms and sleep in human health and disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Circadian rhythms and sleep are fundamental biological processes integral
      to human health. Their disruption is associated with detrimental
      physiological consequences, including cognitive, metabolic, cardiovascular
      and immunological dysfunctions.
    explanation: >-
      This Nature Reviews Genetics review summarizes the genetic architecture
      of circadian and sleep traits, including Mendelian forms of delayed
      sleep-wake phase disorder linked to clock genes.
- name: Altered Melatonin Secretion Timing
  description: >-
    DSPS patients exhibit a delayed dim light melatonin onset (DLMO), reflecting
    a shifted circadian pacemaker. The suprachiasmatic nucleus (SCN) signal to
    the pineal gland for melatonin synthesis is phase-delayed, resulting in later
    endogenous melatonin rise and consequently delayed sleep propensity. This
    delay in melatonin secretion is a hallmark biomarker of the condition.
    However, approximately 40% of DSWPD cases may have normal melatonin timing,
    suggesting heterogeneity in the underlying mechanism.
  cell_types:
  - preferred_term: Pinealocyte
    term:
      id: CL:0000652
      label: pinealocyte
  biological_processes:
  - preferred_term: Melatonin Biosynthetic Process
    term:
      id: GO:0030187
      label: melatonin biosynthetic process
  evidence:
  - reference: PMID:37275982
    reference_title: "Delayed sleep-wake phase disorder and its related sleep behaviors in the young generation."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      individuals with DSWPD without having misalignment of objectively measured
      circadian rhythm markers account for approximately 40% of the cases,
      wherein the psychological and behavioral characteristics of young people,
      such as truancy and academic or social troubles, are largely involved in
      the mechanism of this disorder.
    explanation: >-
      Demonstrates that DSWPD is heterogeneous with respect to melatonin timing,
      with approximately 40% of cases showing normal circadian rhythm markers
      despite delayed sleep schedules, suggesting both circadian-delayed and
      circadian-entrained subtypes.
  - reference: PMID:28388406
    reference_title: "Mutation of the Human Circadian Clock Gene CRY1 in Familial Delayed Sleep Phase Disorder."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Consistent with a phase delay, entrained DLMO occurred at 2:32 am, well
      after the time expected in a subject of normal chronotype (typically
      between 8 to 10 pm) and closer to the time of habitual sleep onset
    explanation: >-
      Demonstrates objectively measured delayed DLMO (2:32 AM vs. normal 8-10 PM)
      in a DSPD proband, confirming delayed melatonin secretion as a marker
      of circadian phase delay.
- name: Impaired Photic Entrainment
  description: >-
    The circadian system normally entrains to the 24-hour light-dark cycle
    through retinal light input to the SCN via melanopsin-containing intrinsically
    photosensitive retinal ganglion cells (ipRGCs). In DSPS, there may be
    increased sensitivity to the melatonin-suppressing effect of evening light,
    and potentially impaired melanopsin-dependent phototransduction, resulting
    in a net phase delay of the circadian oscillator.
  cell_types:
  - preferred_term: Retinal Ganglion Cell
    term:
      id: CL:0000740
      label: retinal ganglion cell
  biological_processes:
  - preferred_term: Entrainment of Circadian Clock
    term:
      id: GO:0009649
      label: entrainment of circadian clock
  evidence:
  - reference: PMID:28388406
    reference_title: "Mutation of the Human Circadian Clock Gene CRY1 in Familial Delayed Sleep Phase Disorder."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The pathophysiology of DSPD remains obscure with suspected causes
      including a differential susceptibility of an individual's circadian clock
      to environmental entrainment cues such as the light/dark cycle, and
      altered properties of the oscillator itself that affect its period length
    explanation: >-
      Identifies altered light entrainment susceptibility as a suspected
      pathophysiological mechanism in DSPD, alongside intrinsic oscillator
      changes.
phenotypes:
- category: VERY_FREQUENT
  name: Sleep Onset Insomnia
  frequency: VERY_FREQUENT
  description: >-
    Inability to fall asleep at a conventional or desired bedtime, with sleep
    onset typically delayed to 2-6 AM. This is the cardinal feature of DSPS.
  phenotype_term:
    preferred_term: Sleep onset insomnia
    term:
      id: HP:0031354
      label: Sleep onset insomnia
  evidence:
  - reference: PMID:37275982
    reference_title: "Delayed sleep-wake phase disorder and its related sleep behaviors in the young generation."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Delayed sleep-wake phase disorder (DSWPD) is a sleep disorder in which
      the habitual sleep-wake timing is delayed, resulting in difficulty in
      falling asleep and waking up at the desired time.
    explanation: >-
      Confirms that difficulty falling asleep at desired times is a defining
      feature of DSWPD.
- category: VERY_FREQUENT
  name: Excessive Daytime Sleepiness
  frequency: VERY_FREQUENT
  description: >-
    When patients must adhere to conventional wake times for work or school,
    the resulting sleep debt causes significant daytime somnolence and
    impaired alertness.
  phenotype_term:
    preferred_term: Excessive daytime sleepiness
    term:
      id: HP:0002329
      label: Drowsiness
  evidence:
  - reference: PMID:37275982
    reference_title: "Delayed sleep-wake phase disorder and its related sleep behaviors in the young generation."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Patients with DSWPD frequently experience fatigue, impaired
      concentration, sleep deprivation during weekdays, and problems of
      absenteeism, which may be further complicated by depressive symptoms.
    explanation: >-
      Documents fatigue, impaired concentration, and sleep deprivation as
      frequent consequences of DSWPD when patients must adhere to conventional
      schedules.
- category: VERY_FREQUENT
  name: Sleep-Wake Cycle Disturbance
  frequency: VERY_FREQUENT
  description: >-
    Extreme difficulty waking at the desired time, often requiring multiple
    alarms and external assistance. The sleep-wake cycle is persistently
    shifted later relative to desired or conventional schedules.
  phenotype_term:
    preferred_term: Sleep-wake cycle disturbance
    term:
      id: HP:0006979
      label: Sleep-wake cycle disturbance
  evidence:
  - reference: PMID:28388406
    reference_title: "Mutation of the Human Circadian Clock Gene CRY1 in Familial Delayed Sleep Phase Disorder."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Delayed Sleep Phase Disorder (DSPD), which is characterized by a
      persistent and intractable delay of sleep onset and offset times relative
      to the societal norm, represents the most commonly diagnosed type of
      circadian rhythm sleep disorder
    explanation: >-
      Confirms persistent delay of both sleep onset and offset times as the
      defining characteristic of DSPD, reflecting a shifted sleep-wake cycle.
- category: FREQUENT
  name: Abnormal Pineal Melatonin Secretion
  frequency: FREQUENT
  description: >-
    Delayed dim light melatonin onset (DLMO) is a hallmark biomarker of
    DSPS, reflecting the delayed circadian phase of the endogenous pacemaker.
    DLMO occurs hours later than in normal sleepers.
  phenotype_term:
    preferred_term: Abnormal pineal melatonin secretion
    term:
      id: HP:0012689
      label: Abnormal pineal melatonin secretion
  evidence:
  - reference: PMID:28388406
    reference_title: "Mutation of the Human Circadian Clock Gene CRY1 in Familial Delayed Sleep Phase Disorder."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Consistent with a phase delay, entrained DLMO occurred at 2:32 am, well
      after the time expected in a subject of normal chronotype (typically
      between 8 to 10 pm) and closer to the time of habitual sleep onset
    explanation: >-
      Documents a markedly delayed DLMO in a DSPD patient, occurring at
      2:32 AM compared to the normal 8-10 PM range.
- category: FREQUENT
  name: Depression
  frequency: FREQUENT
  notes: >-
    Depression is frequently comorbid with DSPS rather than a core phenotype.
    It may be driven by chronic sleep deprivation, circadian misalignment,
    and/or shared genetic factors (CRY1 variant carriers show phenome-wide
    associations with major depressive disorder). Retained as a phenotype
    because the bidirectional relationship and high frequency in DSWPD
    populations make it clinically relevant.
  description: >-
    Depression is frequently comorbid with DSPS, potentially related to
    chronic sleep deprivation and circadian misalignment. CRY1 variant
    carriers show phenome-wide associations with major depressive disorder.
  phenotype_term:
    preferred_term: Depression
    term:
      id: HP:0000716
      label: Depression
  evidence:
  - reference: PMID:37275982
    reference_title: "Delayed sleep-wake phase disorder and its related sleep behaviors in the young generation."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      DSWPD is frequently comorbid with psychiatric disorders, particularly
      mood and neurodevelopmental disorders, both of which have a bidirectional
      association with the pathophysiology of DSWPD.
    explanation: >-
      Establishes frequent comorbidity between DSWPD and mood disorders,
      with a bidirectional pathophysiological relationship.
  - reference: PMID:32538895
    reference_title: "Human CRY1 variants associate with attention deficit/hyperactivity disorder."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      we found in a phenome-wide association study involving 9438 unrelated
      adult Europeans that CRY1Δ11 was associated with major depressive
      disorder, insomnia, and anxiety.
    explanation: >-
      Phenome-wide association study demonstrates that the CRY1 DSPD variant
      is associated with major depressive disorder, providing a genetic link
      between circadian disruption and depression.
- category: FREQUENT
  name: Anxiety
  frequency: FREQUENT
  description: >-
    Patients with DSWPD have a strong tendency toward anxiety, which may
    result in aggravation of insomnia symptoms. CRY1 variant carriers also
    show phenome-wide associations with anxiety.
  phenotype_term:
    preferred_term: Anxiety
    term:
      id: HP:0000739
      label: Anxiety
  evidence:
  - reference: PMID:37275982
    reference_title: "Delayed sleep-wake phase disorder and its related sleep behaviors in the young generation."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      patients with DSWPD have a strong tendency toward neuroticism and
      anxiety, which may result in the aggravation of insomnia symptoms.
    explanation: >-
      Documents the strong association between DSWPD and anxiety traits.
  - reference: PMID:32538895
    reference_title: "Human CRY1 variants associate with attention deficit/hyperactivity disorder."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      we found in a phenome-wide association study involving 9438 unrelated
      adult Europeans that CRY1Δ11 was associated with major depressive
      disorder, insomnia, and anxiety.
    explanation: >-
      Phenome-wide association study links the CRY1 DSPD variant to anxiety.
genetic:
- name: CRY1
  association: Causative
  gene_term:
    preferred_term: CRY1
    term:
      id: hgnc:2384
      label: CRY1
  inheritance:
  - name: Autosomal dominant
    evidence:
    - reference: PMID:28388406
      reference_title: "Mutation of the Human Circadian Clock Gene CRY1 in Familial Delayed Sleep Phase Disorder."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Delayed sleep behavior was found to be common among male and female
        family members and across several generations, consistent with an
        autosomal dominant inheritance pattern
      explanation: >-
        Demonstrates autosomal dominant inheritance of CRY1-related DSPD
        across multiple generations in affected families.
  evidence:
  - reference: PMID:28388406
    reference_title: "Mutation of the Human Circadian Clock Gene CRY1 in Familial Delayed Sleep Phase Disorder."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      we report a hereditary form of DSPD associated with a dominant coding
      variation in the core circadian clock gene CRY1, which creates a
      transcriptional inhibitor with enhanced affinity for circadian activator
      proteins Clock and Bmal1. This gain-of-function CRY1 variant causes
      reduced expression of key transcriptional targets and lengthens the period
      of circadian molecular rhythms, providing a mechanistic link to DSPD
      symptoms. The allele has a frequency of up to 0.6%, and reverse
      phenotyping of unrelated families corroborates late and/or fragmented
      sleep patterns in carriers
    explanation: >-
      Landmark study identifying CRY1 c.1657+3A>C as a gain-of-function variant
      causing familial DSPD with autosomal dominant inheritance and up to
      0.6% allele frequency.
  - reference: PMID:32538895
    reference_title: "Human CRY1 variants associate with attention deficit/hyperactivity disorder."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      One variant, CRY1Δ11 c.1657+3A>C, is present in approximately 1% of
      Europeans, therefore standing out as a diagnostic and therapeutic marker.
      We showed by exome sequencing in an independent cohort of patients with
      combined ADHD and insomnia that 8 of 62 patients and 0 of 369 controls
      carried CRY1Δ11.
    explanation: >-
      Validates CRY1Δ11 as a common variant (~1% in Europeans) enriched in
      patients with ADHD and insomnia, confirming its role in delayed sleep
      phase phenotypes.
- name: PER3
  association: Risk Factor
  gene_term:
    preferred_term: PER3
    term:
      id: hgnc:8847
      label: PER3
  evidence:
  - reference: PMID:12841365
    reference_title: "A length polymorphism in the circadian clock gene Per3 is linked to delayed sleep phase syndrome and extreme diurnal preference."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The Per3 polymorphism correlated significantly with extreme diurnal
      preference, the longer allele associating with morningness and the shorter
      allele with eveningness. The shorter allele was strongly associated with
      the delayed sleep phase syndrome patients, 75% of whom were homozygous.
    explanation: >-
      Establishes the PER3 VNTR polymorphism as a genetic marker for DSPS,
      with the shorter 4-repeat allele strongly associated with DSPS patients.
- name: PER2
  association: Risk Factor
  gene_term:
    preferred_term: PER2
    term:
      id: hgnc:8846
      label: PER2
  evidence:
  - reference: PMID:31527662
    reference_title: "A missense variant in PER2 is associated with delayed sleep-wake phase disorder in a Japanese population."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      A low-frequency missense variant (p.Val1205Met) in PER2 showed a
      significant association with DSWPD (2.5% in cases and 1.1% in controls,
      P = 0.026, odds ratio (OR) = 2.32).
    explanation: >-
      Case-control genetic association data support PER2 p.Val1205Met as a
      DSWPD risk variant in a Japanese population.
environmental:
- name: Evening and Nighttime Light Exposure
  description: >-
    Exposure to artificial light, particularly short-wavelength (blue, ~480 nm)
    light from screens and indoor lighting during evening hours, suppresses
    melatonin secretion and exacerbates circadian phase delay. DSWPD patients
    may have higher photosensitivity to evening light compared to normal
    sleepers, amplifying the phase-delaying effect. The COVID-19 pandemic
    period demonstrated that behavioral changes in light exposure and schedule
    patterns can promote delayed sleep phase.
  evidence:
  - reference: PMID:28388406
    reference_title: "Mutation of the Human Circadian Clock Gene CRY1 in Familial Delayed Sleep Phase Disorder."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The pathophysiology of DSPD remains obscure with suspected causes
      including a differential susceptibility of an individual's circadian clock
      to environmental entrainment cues such as the light/dark cycle, and
      altered properties of the oscillator itself that affect its period length
    explanation: >-
      Identifies differential susceptibility to the light/dark cycle as a
      suspected environmental contributor to DSPD pathophysiology.
  - reference: PMID:37275982
    reference_title: "Delayed sleep-wake phase disorder and its related sleep behaviors in the young generation."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      delayed sleep phase and prolonged sleep duration in the young generation
      have been reported during the period of COVID-19 pandemic-related
      behavioral restrictions. This phenomenon raises a concern about the risk
      of a mismatch between their sleep-wake phase and social life that may
      lead to the development of DSWPD after the removal of these restrictions.
    explanation: >-
      Documents that behavioral restrictions (including altered light exposure
      patterns and schedules) during the pandemic promoted delayed sleep phase,
      supporting environmental contributions to DSWPD development.
- name: Social Jet Lag and Schedule Misalignment
  description: >-
    Mismatch between the individual's endogenous circadian phase and social
    obligations (school, work schedules) exacerbates symptoms and perpetuates
    the delayed phase. Adolescents and young adults are particularly vulnerable
    due to developmental changes in circadian timing that coincide with early
    school start times.
  evidence:
  - reference: PMID:37275982
    reference_title: "Delayed sleep-wake phase disorder and its related sleep behaviors in the young generation."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      DSWPD is typically prevalent during adolescence and young adulthood.
    explanation: >-
      Documents the high prevalence of DSWPD in adolescents and young adults,
      consistent with developmental circadian changes interacting with social
      schedule demands.
diagnosis:
- name: Sleep diary and actigraphy
  description: >-
    Serial sleep diaries combined with actigraphy help document the persistent
    delay in sleep onset and wake timing under real-world conditions and improve
    identification of delayed sleep-wake phase disorder.
  diagnosis_term:
    preferred_term: actigraphy
    term:
      id: MAXO:0000914
      label: actigraphy
  evidence:
  - reference: PMID:40273170
    reference_title: "Delayed sleep-wake phase disorder."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Sleep questionnaires, sleep diaries, and actigraphy have improved
      identification of individuals with delayed sleep.
    explanation: >-
      Review-level guidance supports diary-based sleep logs plus actigraphy as
      practical tools for identifying delayed sleep timing.
- name: Polysomnography when etiology is unclear
  description: >-
    Overnight polysomnography is not required for all cases but can help
    characterize biological versus behavioral contributors, especially when dim
    light melatonin onset testing is unavailable.
  diagnosis_term:
    preferred_term: polysomnography
    term:
      id: MAXO:0000915
      label: polysomnography
  evidence:
  - reference: PMID:34942585
    reference_title: "Delayed Sleep-Wake Phase Disorder: Can Polysomnography Be Useful?"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      We suggest that PSG can provide useful information regarding the
      prevailing etiology (biological versus behavioral) if dim light melatonin
      onset testing is not available.
    explanation: >-
      Adolescent DSWPD cohort data support selective use of PSG to clarify the
      dominant mechanism when circadian phase testing is unavailable.
treatments:
- name: Strategically Timed Melatonin
  description: >-
    Low-dose melatonin (0.5-5 mg) administered in the evening, typically
    3-7 hours before desired sleep onset (relative to DLMO), to phase-advance
    the circadian clock. Dosing time relative to DLMO is more critical than
    dose variation for phase shifting.
  treatment_term:
    preferred_term: melatonin supplementation
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
  evidence:
  - reference: PMID:26414986
    reference_title: "Clinical Practice Guideline for the Treatment of Intrinsic Circadian Rhythm Sleep-Wake Disorders: Advanced Sleep-Wake Phase Disorder (ASWPD), Delayed Sleep-Wake Phase Disorder (DSWPD), Non-24-Hour Sleep-Wake Rhythm Disorder (N24SWD), and Irregular Sleep-Wake Rhythm Disorder (ISWRD). An Update for 2015: An American Academy of Sleep Medicine Clinical Practice Guideline."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Available data allowed for positive endorsement (at a second-tier degree
      of confidence) of strategically timed melatonin (for the treatment of
      DSWPD, blind adults with N24SWD, and children/adolescents with ISWRD
      and comorbid neurological disorders), and light therapy with or without
      accompanying behavioral interventions
    explanation: >-
      AASM Clinical Practice Guideline provides second-tier endorsement for
      strategically timed melatonin in DSWPD treatment.
- name: Bright Light Therapy
  description: >-
    Timed exposure to bright light (2,500-10,000 lux) in the morning, timed
    after the core body temperature minimum or 1-3 hours before spontaneous
    awakening, to phase-advance the circadian clock. The AASM guideline
    endorses light therapy for children and adolescents with DSWPD.
  notes: >-
    No specific MAXO term for bright light therapy/phototherapy for circadian
    disorders currently exists.
  evidence:
  - reference: PMID:26414986
    reference_title: "Clinical Practice Guideline for the Treatment of Intrinsic Circadian Rhythm Sleep-Wake Disorders: Advanced Sleep-Wake Phase Disorder (ASWPD), Delayed Sleep-Wake Phase Disorder (DSWPD), Non-24-Hour Sleep-Wake Rhythm Disorder (N24SWD), and Irregular Sleep-Wake Rhythm Disorder (ISWRD). An Update for 2015: An American Academy of Sleep Medicine Clinical Practice Guideline."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Available data allowed for positive endorsement (at a second-tier degree
      of confidence) of strategically timed melatonin (for the treatment of
      DSWPD, blind adults with N24SWD, and children/adolescents with ISWRD
      and comorbid neurological disorders), and light therapy with or without
      accompanying behavioral interventions
    explanation: >-
      AASM Clinical Practice Guideline provides second-tier endorsement for
      light therapy with or without behavioral interventions specifically for
      children and adolescents with DSWPD; adult DSWPD was not endorsed for
      light therapy in this guideline.
- name: Chronotherapy
  description: >-
    Progressive delay of sleep times around the clock until the desired
    bedtime is reached. This approach exploits the natural tendency toward
    phase delay but requires strict schedule adherence and is difficult
    to maintain long-term.
  notes: >-
    The AASM 2015 guideline did not provide a recommendation for or against
    chronotherapy for DSWPD due to insufficient evidence. No specific MAXO
    term exists for chronotherapy.
  evidence:
  - reference: PMID:26414986
    reference_title: "Clinical Practice Guideline for the Treatment of Intrinsic Circadian Rhythm Sleep-Wake Disorders: Advanced Sleep-Wake Phase Disorder (ASWPD), Delayed Sleep-Wake Phase Disorder (DSWPD), Non-24-Hour Sleep-Wake Rhythm Disorder (N24SWD), and Irregular Sleep-Wake Rhythm Disorder (ISWRD). An Update for 2015: An American Academy of Sleep Medicine Clinical Practice Guideline."
    supports: NO_EVIDENCE
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      No recommendations were provided for remaining treatments/ populations,
      due to either insufficient or absent data.
    explanation: >-
      The AASM guideline could not provide recommendations for chronotherapy
      in DSWPD due to insufficient evidence, reflecting the limited data
      supporting this approach.
- name: Tasimelteon
  description: >-
    A dual MT1/MT2 melatonin receptor agonist under investigation for DSWPD.
    Clinical trials include evaluation in the general DSWPD population and
    in CRY1Δ11 variant carriers specifically. A case report describes symptom
    resolution in a DSWPD patient treated with tasimelteon.
  treatment_term:
    preferred_term: tasimelteon
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
  evidence:
  - reference: DOI:10.3389/fnins.2023.1287514
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The participant was enrolled in an 11-month Open-Label Extension (OLE)
      following the randomized portion of a clinical study and was successfully
      treated with tasimelteon. DSWPD symptoms were resolved, and their
      previously delayed sleep-wake cycle was advanced.
    explanation: >-
      Case report demonstrating successful resolution of DSWPD symptoms with
      tasimelteon treatment, with advancement of the previously delayed
      sleep-wake cycle. Note: this patient had comorbid Optic Nerve Hypoplasia
      (ONH), which commonly impairs photic entrainment and can independently
      cause non-24-hour sleep-wake disorder; this comorbidity limits
      generalizability to uncomplicated DSWPD.
- name: Cognitive-Behavioral Interventions
  description: >-
    Behavioral approaches including sleep hygiene education, stimulus control,
    and cognitive therapy for insomnia-related cognitions. Particularly
    relevant for the circadian-entrained DSWPD subtype where psychological
    and behavioral factors play a larger role.
  treatment_term:
    preferred_term: cognitive and behavioral intervention
    term:
      id: MAXO:0000010
      label: cognitive and behavioral intervention
  evidence:
  - reference: PMID:37275982
    reference_title: "Delayed sleep-wake phase disorder and its related sleep behaviors in the young generation."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      future studies should address the effectiveness of cognitive-behavioral
      approaches in addition to chronobiological approaches in the treatment
      of DSWPD.
    explanation: >-
      Highlights the need for cognitive-behavioral interventions as adjuncts
      to chronobiological treatments, particularly given the circadian-entrained
      subtype where behavioral factors predominate.
clinical_trials:
- name: NCT04652882
  phase: PHASE_III
  status: COMPLETED
  description: >-
    A multicenter, double-blind, randomized study evaluating the efficacy and
    safety of daily oral tasimelteon versus placebo in participants with DSWPD.
  evidence:
  - reference: clinicaltrials:NCT04652882
    supports: SUPPORT
    snippet: >-
      This is a multicenter, double-blind, randomized study to evaluate the
      efficacy and safety of a daily single oral dose of tasimelteon and
      matching placebo in male and female participants with DSWPD.
    explanation: >-
      Phase III trial directly evaluating tasimelteon for DSWPD, the most
      common circadian rhythm sleep disorder.
- name: NCT06701396
  phase: PHASE_III
  status: RECRUITING
  description: >-
    A double-blind, randomized, two-period crossover study evaluating
    tasimelteon versus placebo specifically in patients with DSWPD who carry
    the CRY1Δ11 variant. This precision medicine trial targets the genetically
    defined DSWPD subtype.
  evidence:
  - reference: clinicaltrials:NCT06701396
    supports: SUPPORT
    snippet: >-
      This is a double-blind, randomized, two-period crossover study to
      evaluate the efficacy and safety of a single oral dose of tasimelteon
      and matching placebo in male and female subjects with DSWPD and the
      CRY1Δ11 variant.
    explanation: >-
      First precision medicine trial in DSWPD, targeting patients with the
      CRY1Δ11 genetic variant for tasimelteon treatment.
prevalence:
- population: Global
  percentage: "0.2-10"
  evidence:
  - reference: PMID:28388406
    reference_title: "Mutation of the Human Circadian Clock Gene CRY1 in Familial Delayed Sleep Phase Disorder."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Delayed Sleep Phase Disorder (DSPD), which is characterized by a
      persistent and intractable delay of sleep onset and offset times relative
      to the societal norm, represents the most commonly diagnosed type of
      circadian rhythm sleep disorder with an estimated prevalence of 0.2–10%
      in the general population
    explanation: >-
      Reports the wide prevalence range of DSPD, reflecting heterogeneity in
      manifestation and variation in diagnostic criteria stringency.
- population: Global
  percentage: "3"
  evidence:
  - reference: PMID:37275982
    reference_title: "Delayed sleep-wake phase disorder and its related sleep behaviors in the young generation."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      the prevalence of DSWPD is estimated to be approximately 3% with little
      racial differences between Caucasians and Asians
    explanation: >-
      Provides a consensus prevalence estimate of approximately 3% with
      minimal racial differences.
inheritance:
- name: Complex/Multifactorial
  evidence:
  - reference: PMID:28388406
    reference_title: "Mutation of the Human Circadian Clock Gene CRY1 in Familial Delayed Sleep Phase Disorder."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      many classical twin studies have found a strong hereditary component to
      chronotype preference in the range of 40–50%, arguing for an important
      role of genetic predisposition to DSPD etiology
    explanation: >-
      Twin studies demonstrate 40-50% heritability of chronotype preference,
      supporting a significant genetic contribution to DSPS susceptibility.
- name: Autosomal dominant (CRY1 subtype)
  evidence:
  - reference: PMID:28388406
    reference_title: "Mutation of the Human Circadian Clock Gene CRY1 in Familial Delayed Sleep Phase Disorder."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Delayed sleep behavior was found to be common among male and female
      family members and across several generations, consistent with an
      autosomal dominant inheritance pattern
    explanation: >-
      Demonstrates autosomal dominant inheritance of CRY1-related DSPD across
      multiple generations in affected families.
classifications:
  harrisons_chapter:
  - classification_value: NEUROLOGIC
    evidence:
    - reference: PMID:29445534
      reference_title: "Delayed sleep-wake phase disorder."
      supports: SUPPORT
      evidence_source: OTHER
      snippet: >-
        Delayed sleep-wake phase disorder (DSWPD) is the most commonly
        encountered of the circadian rhythm sleep-wake disorders (CRSDs),
      explanation: >-
        Supports classification as a nervous-system proxy in the current schema,
        which lacks a dedicated sleep/circadian Harrison chapter.
📚

References & Deep Research

Deep Research

1
Falcon ▸
Disease Pathophysiology Research Template
Edison Scientific Literature 34 citations 2026-02-26T17:57:57.604032

Question: You are an expert researcher providing comprehensive, well-cited information.

Provide detailed information focusing on: 1. Key concepts and definitions with current understanding 2. Recent developments and latest research (prioritize 2023-2024 sources) 3. Current applications and real-world implementations 4. Expert opinions and analysis from authoritative sources 5. Relevant statistics and data from recent studies

Format as a comprehensive research report with proper citations. Include URLs and publication dates where available. Always prioritize recent, authoritative sources and provide specific citations for all major claims.

Disease Pathophysiology Research Template

Target Disease

  • Disease Name: Delayed Sleep Phase Syndrome
  • MONDO ID: (if available)
  • Category: Complex

Research Objectives

Please provide a comprehensive research report on the pathophysiology of Delayed Sleep Phase Syndrome. Focus on the molecular and cellular mechanisms underlying disease progression.

Required Information

1. Core Pathophysiology

  • What are the primary pathophysiological mechanisms?
  • What molecular pathways are dysregulated?
  • What cellular processes are affected?

2. Key Molecular Players

  • Genes/Proteins: Which genes are causally involved or implicated?
  • Chemical Entities: What metabolites, drugs, or small molecules are relevant?
  • Cell Types: Which cell types are primarily affected?
  • Anatomical Locations: Which tissues/organs are involved?

3. Biological Processes (for GO annotation)

  • What biological processes (GO terms) are disrupted?
  • Consider: signaling pathways, metabolic processes, cellular responses, transport, etc.

4. Cellular Components

  • Where in the cell do key processes occur?
  • Consider: organelles, membrane compartments, extracellular space, etc.

5. Disease Progression

  • What is the sequence of events from initial trigger to clinical manifestation?
  • Are there distinct stages or phases?

6. Phenotypic Manifestations

  • What are the key clinical phenotypes?
  • How do they relate to the underlying mechanisms?

Citation Requirements

  • Cite primary literature (PMID preferred) for all mechanistic claims
  • Prioritize recent reviews and landmark papers
  • Include direct quotes where possible to support key statements

Output Format

Structure your response as a narrative that could be used to populate a disease knowledge base entry with: - Pathophysiology description - Gene/protein annotations with ontology terms (HGNC, GO) - Phenotype associations (HP terms) - Cell type involvement (CL terms) - Anatomical locations (UBERON terms) - Chemical entities (CHEBI terms) - Evidence items with PMIDs

Title: Pathophysiology of Delayed Sleep Phase Syndrome / Delayed Sleep–Wake Phase Disorder (DSPS/DSWPD)

Publication date: 2026-02-27

  1. Disease identifiers and definition

Disease name and nosology Delayed Sleep Phase Syndrome (DSPS) is now commonly termed Delayed Sleep–Wake Phase Disorder (DSWPD) in modern classifications. It is defined by a persistent delay of the major sleep period relative to desired or socially required times, causing difficulty falling asleep and waking at desired times, with functional impairment. (futenma2023delayedsleep–wakephase pages 1-2, consens2023circadianrhythmsleepwake pages 155-156)

MONDO ID A MONDO identifier was not available in the retrieved sources and could not be verified in this run.

Key circadian concepts/definitions • Zeitgeber: The primary environmental time cue for entrainment of the circadian clock; in humans, light is emphasized as dominant (see below). (futenma2023delayedsleep–wakephase pages 3-4) • Circadian phase markers: Dim light melatonin onset (DLMO), core body temperature (CBT) minimum (CBTmin), and related rhythms used to infer circadian timing. (futenma2023delayedsleep–wakephase pages 3-4, wu2023updatesandconfounding pages 1-2) • Phase angle of entrainment: The phase relationship between circadian markers (e.g., DLMO/CBT rhythm) and sleep timing. (futenma2023delayedsleep–wakephase pages 1-2) • Intrinsic circadian period (“tau”): Individual endogenous period length; longer tau predisposes to later entrained phase. (futenma2023delayedsleep–wakephase pages 3-4, futenma2023delayedsleep–wakephase pages 2-3)

  1. Core pathophysiology (molecular/cellular mechanisms)

2.1 Central mechanism: delayed circadian phase and altered entrainment DSWPD is often conceptualized as a disorder of delayed circadian timing relative to the external light–dark cycle and social timing demands. In clinical/review literature, delayed circadian phase is typically indexed by delayed DLMO and/or CBT rhythms in a substantial subset. (futenma2023delayedsleep–wakephase pages 3-4, futenma2023delayedsleep–wakephase pages 8-10)

Light–SCN entrainment and downstream melatonin rhythm The SCN (suprachiasmatic nucleus) is explicitly identified as the generator of key circadian outputs: CBT and melatonin rhythms are described as “generated by the SCN” and as “well-established indicators of circadian rhythms.” (futenma2023delayedsleep–wakephase pages 3-4) Mechanistically, light influences SCN firing and clock gene transcription: Futenma et al. describe that light stimulation at specific times can alter SCN firing and “activates molecular signaling and clock-gene transcription,” regulating melatonin rhythms. (futenma2023delayedsleep–wakephase pages 2-3)

Direct quotable statements supporting light-driven entrainment and variability • “light stimulation is the most important zeitgeber” (futenma2023delayedsleep–wakephase pages 3-4) • “individual sensitivity to light varies 50-fold on a logarithmic scale” (futenma2023delayedsleep–wakephase pages 3-4) • DLMO definition/measurement: “DLMO, which is measured in light less than 10 lx, enables the estimation of the circadian phase of melatonin secretion.” (futenma2023delayedsleep–wakephase pages 3-4)

Intrinsic period (tau) as a mechanism predisposing to delay Futenma et al. explicitly link longer tau to later entrained phase: “The length of tau varies among individuals, and individuals with longer tau are entrained at a later phase.” (futenma2023delayedsleep–wakephase pages 3-4) They also provide an estimated mean intrinsic period: ~24.15 h (SD 0.2 h) and note sex differences (~6 minutes shorter in women). (futenma2023delayedsleep–wakephase pages 2-3)

Altered light sensitivity and phase response DSWPD may involve increased sensitivity to night light, which can increase phase delays. Futenma et al. report: “photosensitivity at night is higher in patients with DSWPD than in normal sleepers, which may contribute to the delay in circadian rhythm.” (futenma2023delayedsleep–wakephase pages 3-4) Wu’s 2023 review summarizes converging evidence that DSWPD patients can be especially sensitive to the melatonin-suppressing effect of light, particularly in the pre-DLMO window, and may exhibit a reduced melatonin surge; it also discusses hypothesized alterations in the phase response curve (PRC) that could make phase advances harder to achieve. (wu2023updatesandconfounding pages 4-5)

2.2 Pathophysiology beyond circadian delay: subtype heterogeneity and sleep homeostasis

Circadian-delayed vs circadian-entrained subtypes A key recent refinement is that not all patients with clinically delayed sleep timing show delayed objective circadian markers. Futenma et al. state that “approximately 40% … of patients with DSWPD have normal timing of melatonin secretion profile … even though their sleep–wake schedule is clearly delayed,” describing this subgroup as “circadian-entrained DSWPD.” (futenma2023delayedsleep–wakephase pages 1-2) The same review reiterates that ~40% of cases may be circadian-entrained and that behavioral/psychological factors can enlarge the phase angle between DLMO and sleep onset (instead of a delayed DLMO). (futenma2023delayedsleep–wakephase pages 8-10)

Sleep homeostasis alterations Wu (2023) emphasizes that DSWPD is commonly viewed as purely circadian, but accumulating evidence suggests sleep-homeostatic differences relative to controls. Reported patterns include slower build-up and slower dissipation of sleep pressure and altered recovery sleep dynamics in evening types/DSWPD. (wu2023updatesandconfounding pages 4-5, wu2023updatesandconfounding pages 5-6) This supports a two-process pathophysiology model in which both circadian and homeostatic processes contribute to the phenotype in different individuals. (wu2023updatesandconfounding pages 4-5, wu2023updatesandconfounding pages 5-6)

  1. Key molecular players (genes/proteins, small molecules, cell types, anatomy)

3.1 Genes and proteins (HGNC-level entities)

Core circadian clock genes implicated in sleep-wake phase disorders A 2023 Nature Reviews Genetics synthesis reports Mendelian forms of advanced/delayed sleep-wake phase disorders and lists implicated clock genes: PER2, PER3, CRY1, CRY2, CSNK1D, and TIMELESS. Functional follow-up links variants to altered circadian period length and altered entrainment to light, with phosphorylation changes supported in model systems. (lane2023geneticsofcircadian pages 6-7) In broader human genetic studies of circadian timing, additional loci include ARNTL (BMAL1), PER1, VIP, RGS16, PATJ, and HCRTR2 (orexin receptor 2) among others. (lane2023geneticsofcircadian pages 4-6)

CRY1 as a high-confidence mechanistic gene for delayed sleep phase phenotypes A 2023 Journal of Clinical Investigation study provides direct mechanistic evidence for CRY1 splice variants associated with delayed sleep phase disorder (DSPD) in families. It describes CRY1 as a core clock repressor that “represses the activity of the transcription factors CLOCK and BMAL1 transactivation.” (onat2023humancry1variants pages 2-3) Key variant-mechanism links include: • CRY1Δ11 (c.1657+3A>C; rs184039278): described as gain-of-function and associated with delayed sleep phase phenotypes; the paper reports it is present at ~1% frequency in Europeans. (onat2023humancry1variants pages 1-2) • Enrichment in a validation cohort: 8/62 patients with combined ADHD and insomnia carried CRY1Δ11 vs 0/369 controls. (onat2023humancry1variants pages 1-2) • Period effect size: CRY1Δ11 lengthens the circadian period by ~26 minutes versus wild-type. (onat2023humancry1variants pages 5-9) • CRY1Δ6 (c.825+1G>A): exon-6 skipping variant showing reduced BMAL1/CLOCK affinity and an arrhythmic phenotype, segregating with ADHD and DSPD in the family studied. (onat2023humancry1variants pages 1-2, onat2023humancry1variants pages 9-10) These observations connect molecular clock repression dynamics (CRY1–CLOCK/BMAL1 complex) to human delayed sleep phase phenotypes. (onat2023humancry1variants pages 1-2, onat2023humancry1variants pages 5-9)

Expression-phase biology in peripheral cells Wu (2023) cites evidence that inter-individual differences in habitual sleep timing map to the entrained phase of endogenous circadian rhythms of BMAL1, PER2, and PER3 mRNA in human leukocytes. (wu2023updatesandconfounding pages 6-7)

3.2 Chemical entities / small molecules (ChEBI-level entities)

Endogenous melatonin (ChEBI:17195) Melatonin phase (DLMO) is a key physiological marker and mechanistic effector of circadian timing. DLMO-based quantification is described as a practical estimate of melatonin phase. (futenma2023delayedsleep–wakephase pages 3-4, wu2023updatesandconfounding pages 1-2)

Exogenous melatonin (chronobiotic) Exogenous melatonin shifts circadian phase. Wu (2023) states that when melatonin is “taken in the early evening prior to DLMO it advances the circadian phase,” consistent with a PRC that is roughly inverse to light. (wu2023updatesandconfounding pages 1-2) Clinical trial implementation includes nightly 0.5 mg fast-dissolve melatonin for 28 days, timed relative to DLMO (measured vs estimated) to test whether biomarker-based timing produces greater phase shifts. (NCT03715465 chunk 1)

Melatonin receptor agonists (chronobiotics) • Tasimelteon (dual MT1/MT2 agonist): a case report and related trial program describe it as a melatonin receptor agonist with high affinity for MT1 and MT2 that can entrain circadian sleep phase timing; a DSWPD clinical program includes a multicenter randomized component with an 11-month open-label extension dosing 60 minutes before desired bedtime. (smieszek2023casereporta pages 1-2) • Ramelteon is discussed as a melatonin receptor agonist with limited evidence (case reports) in DSWPD, and randomized trials are noted as lacking in Wu’s review. (wu2023updatesandconfounding pages 4-5, wu2023updatesandconfounding pages 8-9)

Light (short-wavelength/blue ~480 nm as a functional “chemical-like” stimulus) Although not a chemical entity, short-wavelength light (~480 nm) is repeatedly identified as particularly potent for melatonin suppression and circadian phase effects. Futenma et al. note circadian rhythms are most sensitive to ~480 nm blue light and that melatonin suppression is more potent at these wavelengths, which has implications for optimizing light therapy or for evening blue-light restriction. (futenma2023delayedsleep–wakephase pages 8-10)

3.3 Cell types (Cell Ontology-level entities)

Intrinsically photosensitive retinal ganglion cells (ipRGCs; melanopsin-positive) ipRGCs are described as integrating rod/cone signals and driving non-visual functions including circadian entrainment and the pupillary light response. (hartstein2024differencesinthe pages 1-2) Schöllhorn et al. (2024) note melanopsin is expressed by ipRGCs, which project to the SCN for circadian photoentrainment and to the olivary pretectal nucleus for pupil reflexes. (schollhorn2024theimpactof pages 1-2) Disease-relevance: a cited study within a 2023 DSWPD case report explicitly states “Melanopsin-dependent phototransduction is impaired in delayed sleep-wake phase disorder,” suggesting a retinal non-visual photoreception contribution to DSWPD in at least some patients. (smieszek2023casereporta pages 5-5)

Peripheral leukocytes Peripheral blood leukocytes are used in human studies measuring circadian-phase of BMAL1/PER2/PER3 mRNA rhythms linked to habitual sleep timing. (wu2023updatesandconfounding pages 6-7)

3.4 Anatomical locations (UBERON-level entities)

Key tissues/structures • Suprachiasmatic nucleus (SCN; hypothalamus): central pacemaker; source of CBT/melatonin rhythmic outputs and site of light-driven resetting. (futenma2023delayedsleep–wakephase pages 3-4, futenma2023delayedsleep–wakephase pages 2-3) • Retina (including ipRGCs): transduces light for non-image-forming circadian entrainment; melanopsin pathway implicated. (hartstein2024differencesinthe pages 1-2, schollhorn2024theimpactof pages 1-2) • Pineal gland (implied via melatonin secretion physiology; not explicitly asserted in the extracted excerpts).

  1. Dysregulated pathways and cellular processes

4.1 Canonical molecular clock transcriptional feedback DSWPD-associated variants implicate core transcriptional repression of the CLOCK/BMAL1 complex by CRY1. The JCI paper explicitly states CRY1 “represses the activity of the transcription factors CLOCK and BMAL1.” (onat2023humancry1variants pages 2-3) This maps to dysregulation of circadian transcriptional/translational feedback loops (TTFL), impacting circadian period length and phase stability. (onat2023humancry1variants pages 5-9, lane2023geneticsofcircadian pages 6-7)

4.2 Light input pathway and non-visual phototransduction ipRGC/melanopsin-mediated phototransduction provides a mechanistic route by which evening light can suppress melatonin and delay circadian phase. ipRGCs are described as key drivers of circadian entrainment. (hartstein2024differencesinthe pages 1-2, schollhorn2024theimpactof pages 1-2) Impaired melanopsin-dependent phototransduction has been reported in DSWPD (quoted in a DSWPD case report’s cited literature), suggesting that abnormal retinal light signaling could contribute to altered entrainment. (smieszek2023casereporta pages 5-5)

4.3 Sleep homeostasis and circadian–homeostatic interaction Wu (2023) summarizes evidence for differences in sleep pressure dynamics in DSWPD/evening types and notes interactions between sleep history and circadian processes (including effects of sleep deprivation on clock gene expression in model systems and the possibility that sleep–wake patterns can modify SCN entrainment). (wu2023updatesandconfounding pages 5-6)

  1. Biological processes and cellular components (GO-oriented mapping)

5.1 Candidate disrupted GO Biological Process terms (examples for knowledge-base annotation) • GO:0007623 circadian rhythm (core disrupted process; altered phase/period). (futenma2023delayedsleep–wakephase pages 3-4, lane2023geneticsofcircadian pages 6-7) • GO:0007622 rhythm of circadian clock (period lengthening by CRY1Δ11; arrhythmic phenotype for CRY1Δ6). (onat2023humancry1variants pages 5-9, onat2023humancry1variants pages 9-10) • GO:0042752 regulation of circadian rhythm (light/melatonin phase-resetting; SCN-dependent regulation). (futenma2023delayedsleep–wakephase pages 2-3, wu2023updatesandconfounding pages 1-2) • GO:0009416 response to light stimulus (ipRGC/melanopsin signaling affecting melatonin and phase). (hartstein2024differencesinthe pages 1-2, schollhorn2024theimpactof pages 1-2) • GO:0032922 circadian regulation of gene expression (leukocyte BMAL1/PER2/PER3 mRNA phases relate to sleep timing). (wu2023updatesandconfounding pages 6-7) • GO:0048511 rhythmic process (broad umbrella for coupled circadian and homeostatic changes). (wu2023updatesandconfounding pages 5-6)

5.2 Candidate GO Cellular Component terms (where processes occur) • SCN neurons: hypothalamic neuronal circuits generating circadian outputs (SCN referenced explicitly). (futenma2023delayedsleep–wakephase pages 3-4, futenma2023delayedsleep–wakephase pages 2-3) • Nucleus (CLOCK/BMAL1 transcriptional regulation; CRY1 repression implies nuclear transcriptional complexes). (onat2023humancry1variants pages 2-3) • Retina / retinal ganglion cell layer: site of melanopsin-mediated phototransduction (ipRGCs). (hartstein2024differencesinthe pages 1-2, schollhorn2024theimpactof pages 1-2)

  1. Disease progression model (sequence from trigger to phenotype)

A mechanistic sequence consistent with recent reviews is: 1) Predisposing factors: genetic variants affecting clock period or repression strength (e.g., CRY1Δ11 lengthening period; other rare variants in PER/CRY/CSNK1D/TIMELESS), plus developmental tendency to delayed melatonin timing during adolescence and behavioral/environmental drivers (late-night light exposure, social schedules). (onat2023humancry1variants pages 5-9, lane2023geneticsofcircadian pages 6-7, feder2024justletme pages 7-9) 2) Entrainment imbalance: longer tau and/or altered PRC makes phase advances less likely; increased evening/night light sensitivity and evening screen exposure suppress melatonin and push phase later. (futenma2023delayedsleep–wakephase pages 3-4, wu2023updatesandconfounding pages 4-5) 3) Circadian misalignment: delayed DLMO/CBT rhythm relative to desired bed/wake time; or, in circadian-entrained DSWPD, normal DLMO but an enlarged phase angle due to behavior/psychological factors. (futenma2023delayedsleep–wakephase pages 1-2, futenma2023delayedsleep–wakephase pages 8-10) 4) Clinical syndrome: sleep-onset insomnia at conventional bedtime, difficulty awakening at required times, daytime impairment (fatigue, impaired concentration), social/academic/work dysfunction; relapse risk after treatment is commonly described. (futenma2023delayedsleep–wakephase pages 1-2, wu2023updatesandconfounding pages 1-2)

  1. Phenotypic manifestations and ontology mapping

7.1 Core clinical phenotypes (Human Phenotype Ontology; examples) • Delayed sleep phase / delayed sleep onset (concept supported by definition and mechanistic delay). (futenma2023delayedsleep–wakephase pages 1-2, consens2023circadianrhythmsleepwake pages 155-156) • Sleep-onset insomnia (explicitly noted as common in DSWPD). (consens2023circadianrhythmsleepwake pages 150-152) • Difficulty waking / delayed wake time (by definition and treatment targets). (consens2023circadianrhythmsleepwake pages 155-156) • Daytime sleepiness / impaired daytime function (noted in DSWPD context and treatment goals). (smieszek2023casereporta pages 1-2)

7.2 Psychiatric/neurodevelopmental comorbidity DSWPD is frequently comorbid with psychiatric disorders; CRY1-related families show strong co-segregation with ADHD and DSPD, and phenome-wide associations link CRY1Δ11 with major depressive disorder, insomnia, and anxiety. (onat2023humancry1variants pages 2-3, onat2023humancry1variants pages 9-10)

  1. Recent developments (2023–2024 focus)

8.1 Subtyping: “circadian-delayed” versus “circadian-entrained” DSWPD A major 2023 synthesis emphasizes that ~40% of patients may have normal melatonin timing despite delayed sleep schedules, reframing DSWPD as heterogeneous rather than uniformly “delayed DLMO.” (futenma2023delayedsleep–wakephase pages 1-2, futenma2023delayedsleep–wakephase pages 8-10)

8.2 Precision genetics: CRY1 splice variants and clinical translation The 2023 JCI study provides a strong mechanistic bridge from genotype → altered CLOCK/BMAL1 repression and altered period/arrhythmicity → delayed sleep phase phenotype. It also provides population frequency estimates for CRY1Δ11 (~1% frequency in Europeans) and suggests it may serve as a diagnostic marker in relevant subgroups. (onat2023humancry1variants pages 1-2, onat2023humancry1variants pages 5-9)

8.3 Retinal non-visual photoreception as a mechanistic focus 2024 work continues to refine measurement and mechanistic interpretation of melanopsin/ipRGC signaling in humans, including silent-substitution approaches and melanopic irradiance metrics linked to melatonin suppression and pupil dynamics. These methods strengthen mechanistic inference about the light input pathway relevant to phase-delaying evening light. (schollhorn2024theimpactof pages 1-2) The statement that “Melanopsin-dependent phototransduction is impaired in delayed sleep-wake phase disorder” highlights an actionable mechanistic hypothesis for a subset of DSWPD patients (retinal/circadian input phenotype). (smieszek2023casereporta pages 5-5)

  1. Current applications and real-world implementations

9.1 Light-based circadian phase advance (clinical protocols) Light therapy is described as first-line in some clinical guidance. Futenma et al. report protocols of 2,500–10,000 lux for 30 minutes to 2 hours, timed to the morning (after CBTmin) or 1–3 hours before spontaneous awakening to phase-advance. (futenma2023delayedsleep–wakephase pages 8-10) Consens (2023) gives implementable advice: dim light for 2 hours before bedtime to facilitate endogenous melatonin release and ~60 minutes of bright light after waking to advance phase; a 30-minute bright-light maintenance regimen is suggested after stabilization. (consens2023circadianrhythmsleepwake pages 150-152, consens2023circadianrhythmsleepwake pages 155-156)

9.2 Melatonin timed to circadian phase (DLMO-guided treatment) A key translational application is biomarker-guided melatonin timing. The University of Michigan trial NCT03715465 tests nightly 0.5 mg melatonin timed 3 hours before measured DLMO vs 3 hours before estimated DLMO, with DLMO shift as a primary endpoint. (NCT03715465 chunk 1) Wu (2023) emphasizes that dosing time relative to DLMO is more critical than dose variation for phase shifting. (wu2023updatesandconfounding pages 1-2)

9.3 Tasimelteon development in DSWPD • NCT04652882 (Vanda; Phase 3): randomized, placebo-controlled trial evaluating daily tasimelteon for 28 days with sleep-onset change by diary as primary endpoint. (NCT04652882 chunk 1) • NCT06701396 (Vanda; Phase 3, 2024 start): a precision-medicine trial restricted to DSWPD patients carrying CRY1Δ11, using a double-blind crossover single-dose design with polysomnography-derived latency to persistent sleep as primary outcome. (NCT06701396 chunk 1) A 2023 Frontiers in Neuroscience case report describes tasimelteon as a high-affinity MT1/MT2 agonist that acts by entraining circadian sleep phase timing and reports symptom resolution in an adult DSWPD patient (with optic nerve hypoplasia) with confirmed delayed DLMO. (smieszek2023casereporta pages 1-2)

  1. Relevant statistics and quantitative data (recent sources)

Prevalence • DSWPD prevalence is estimated at approximately ~3%. (futenma2023delayedsleep–wakephase pages 1-2, lane2023geneticsofcircadian pages 6-7)

Subtype proportion • Approximately ~40% of clinically diagnosed DSWPD may have normal melatonin timing (“circadian-entrained DSWPD”). (futenma2023delayedsleep–wakephase pages 1-2, futenma2023delayedsleep–wakephase pages 8-10)

Quantitative physiology • Light sensitivity variability: “individual sensitivity to light varies 50-fold on a logarithmic scale.” (futenma2023delayedsleep–wakephase pages 3-4) • Intrinsic period: mean tau ~24.15 h (SD 0.2 h), with women ~6 minutes shorter than men. (futenma2023delayedsleep–wakephase pages 2-3)

Quantitative genetics • CRY1Δ11 frequency: described as ~1% in Europeans. (onat2023humancry1variants pages 1-2) • CRY1Δ11 functional period effect: lengthens circadian period by ~26 minutes. (onat2023humancry1variants pages 5-9)

  1. Expert interpretation and analysis (synthesis across sources)

Current best-supported mechanistic model Recent reviews converge on a multi-factorial pathophysiology in which delayed phase arises from an interplay of (i) intrinsic circadian properties (tau, PRC characteristics), (ii) environmental light exposure patterns (especially evening/night light with high melanopic content), (iii) genetic variants in core clock genes that change period length or entrainment properties (e.g., CRY1 splice variants), and (iv) in a substantial subset, non-circadian contributors including altered sleep homeostasis and behavioral/psychological patterns that widen the phase angle without delayed DLMO. (futenma2023delayedsleep–wakephase pages 3-4, wu2023updatesandconfounding pages 4-5, lane2023geneticsofcircadian pages 6-7, wu2023updatesandconfounding pages 5-6)

Clinical implications The heterogeneity (circadian-delayed vs circadian-entrained) supports personalized treatment selection: circadian-delayed cases are plausibly most responsive to PRC-informed circadian phase shifting (morning bright light, evening dim light, correctly timed melatonin/MT1–MT2 agonists), whereas circadian-entrained cases may require greater emphasis on behavioral/cognitive interventions and sleep scheduling to address maladaptive phase angle and insomnia-maintaining factors. (futenma2023delayedsleep–wakephase pages 1-2, wu2023updatesandconfounding pages 4-5)

  1. Evidence items (PMID notes) PMIDs were not present in the extracted text snippets for the key primary genetic study (Onat et al., J Clin Invest 2023) or the cited reviews; therefore, PMID identifiers cannot be provided from the retrieved context in this run. DOI/URLs and publication months/years are provided in the citations above.

URLs and publication dates for key cited sources (from retrieved metadata) • Futenma et al. “Delayed sleep–wake phase disorder and its related sleep behaviors in the young generation.” Frontiers in Psychiatry. May 2023. https://doi.org/10.3389/fpsyt.2023.1174719 (futenma2023delayedsleep–wakephase pages 1-2) • Wu A. “Updates and confounding factors in delayed sleep–wake phase disorder.” Sleep and Biological Rhythms. Mar 2023. https://doi.org/10.1007/s41105-023-00454-4 (wu2023updatesandconfounding pages 4-5) • Lane et al. “Genetics of circadian rhythms and sleep in human health and disease.” Nature Reviews Genetics. Aug 2023. https://doi.org/10.1038/s41576-022-00519-z (lane2023geneticsofcircadian pages 6-7) • Consens FB. “Circadian rhythm sleep-wake disorders.” CONTINUUM. Aug 2023. https://doi.org/10.1212/con.0000000000001287 (consens2023circadianrhythmsleepwake pages 155-156) • Onat et al. “Human CRY1 variants associate with attention deficit/hyperactivity disorder.” Journal of Clinical Investigation. Jun 2023. https://doi.org/10.1172/jci135500 (onat2023humancry1variants pages 1-2) • Smieszek et al. “Case report: A patient with DSWPD and optic nerve hypoplasia treated with tasimelteon.” Frontiers in Neuroscience. Nov 2023. https://doi.org/10.3389/fnins.2023.1287514 (smieszek2023casereporta pages 1-2) • Schöllhorn et al. “The impact of pupil constriction on the relationship between melanopic EDI and melatonin suppression…” Journal of Biological Rhythms. Feb 2024. https://doi.org/10.1177/07487304241226466 (schollhorn2024theimpactof pages 1-2) • Hartstein et al. “Differences in the pupillary responses to evening light between children and adolescents.” Journal of Physiological Anthropology. Jul 2024. https://doi.org/10.1186/s40101-024-00363-6 (hartstein2024differencesinthe pages 1-2)

ClinicalTrials.gov URLs (registry entries) • NCT04652882 (Vanda; first posted 2020; Phase 3; DSWPD tasimelteon vs placebo): https://clinicaltrials.gov/study/NCT04652882 (NCT04652882 chunk 1) • NCT06701396 (Vanda; start date 2024-10-08; Phase 3; tasimelteon vs placebo in CRY1Δ11 carriers): https://clinicaltrials.gov/study/NCT06701396 (NCT06701396 chunk 1) • NCT03715465 (University of Michigan; melatonin timing with measured vs estimated DLMO): https://clinicaltrials.gov/study/NCT03715465 (NCT03715465 chunk 1)

References

  1. (futenma2023delayedsleep–wakephase pages 1-2): Kunihiro Futenma, Yoshikazu Takaesu, Yoko Komada, Akiyoshi Shimura, Isa Okajima, Kentaro Matsui, Kosuke Tanioka, and Yuichi Inoue. Delayed sleep–wake phase disorder and its related sleep behaviors in the young generation. Frontiers in Psychiatry, May 2023. URL: https://doi.org/10.3389/fpsyt.2023.1174719, doi:10.3389/fpsyt.2023.1174719. This article has 37 citations.

  2. (consens2023circadianrhythmsleepwake pages 155-156): Flavia B. Consens. Circadian rhythm sleep-wake disorders. CONTINUUM: Lifelong Learning in Neurology, 29:1149-1166, Aug 2023. URL: https://doi.org/10.1212/con.0000000000001287, doi:10.1212/con.0000000000001287. This article has 7 citations.

  3. (futenma2023delayedsleep–wakephase pages 3-4): Kunihiro Futenma, Yoshikazu Takaesu, Yoko Komada, Akiyoshi Shimura, Isa Okajima, Kentaro Matsui, Kosuke Tanioka, and Yuichi Inoue. Delayed sleep–wake phase disorder and its related sleep behaviors in the young generation. Frontiers in Psychiatry, May 2023. URL: https://doi.org/10.3389/fpsyt.2023.1174719, doi:10.3389/fpsyt.2023.1174719. This article has 37 citations.

  4. (wu2023updatesandconfounding pages 1-2): Alexandra Wu. Updates and confounding factors in delayed sleep–wake phase disorder. Sleep and Biological Rhythms, 21:279-287, Mar 2023. URL: https://doi.org/10.1007/s41105-023-00454-4, doi:10.1007/s41105-023-00454-4. This article has 7 citations and is from a peer-reviewed journal.

  5. (futenma2023delayedsleep–wakephase pages 2-3): Kunihiro Futenma, Yoshikazu Takaesu, Yoko Komada, Akiyoshi Shimura, Isa Okajima, Kentaro Matsui, Kosuke Tanioka, and Yuichi Inoue. Delayed sleep–wake phase disorder and its related sleep behaviors in the young generation. Frontiers in Psychiatry, May 2023. URL: https://doi.org/10.3389/fpsyt.2023.1174719, doi:10.3389/fpsyt.2023.1174719. This article has 37 citations.

  6. (futenma2023delayedsleep–wakephase pages 8-10): Kunihiro Futenma, Yoshikazu Takaesu, Yoko Komada, Akiyoshi Shimura, Isa Okajima, Kentaro Matsui, Kosuke Tanioka, and Yuichi Inoue. Delayed sleep–wake phase disorder and its related sleep behaviors in the young generation. Frontiers in Psychiatry, May 2023. URL: https://doi.org/10.3389/fpsyt.2023.1174719, doi:10.3389/fpsyt.2023.1174719. This article has 37 citations.

  7. (wu2023updatesandconfounding pages 4-5): Alexandra Wu. Updates and confounding factors in delayed sleep–wake phase disorder. Sleep and Biological Rhythms, 21:279-287, Mar 2023. URL: https://doi.org/10.1007/s41105-023-00454-4, doi:10.1007/s41105-023-00454-4. This article has 7 citations and is from a peer-reviewed journal.

  8. (wu2023updatesandconfounding pages 5-6): Alexandra Wu. Updates and confounding factors in delayed sleep–wake phase disorder. Sleep and Biological Rhythms, 21:279-287, Mar 2023. URL: https://doi.org/10.1007/s41105-023-00454-4, doi:10.1007/s41105-023-00454-4. This article has 7 citations and is from a peer-reviewed journal.

  9. (lane2023geneticsofcircadian pages 6-7): Jacqueline M. Lane, Jingyi Qian, Emmanuel Mignot, Susan Redline, Frank A. J. L. Scheer, and Richa Saxena. Genetics of circadian rhythms and sleep in human health and disease. Nature Reviews Genetics, 24:4-20, Aug 2023. URL: https://doi.org/10.1038/s41576-022-00519-z, doi:10.1038/s41576-022-00519-z. This article has 243 citations and is from a domain leading peer-reviewed journal.

  10. (lane2023geneticsofcircadian pages 4-6): Jacqueline M. Lane, Jingyi Qian, Emmanuel Mignot, Susan Redline, Frank A. J. L. Scheer, and Richa Saxena. Genetics of circadian rhythms and sleep in human health and disease. Nature Reviews Genetics, 24:4-20, Aug 2023. URL: https://doi.org/10.1038/s41576-022-00519-z, doi:10.1038/s41576-022-00519-z. This article has 243 citations and is from a domain leading peer-reviewed journal.

  11. (onat2023humancry1variants pages 2-3): O. Emre Onat, M. Ece Kars, Şeref Gül, Kaya Bilguvar, Yiming Wu, Ayşe Özhan, Cihan Aydın, A. Nazlı Başak, M. Allegra Trusso, Arianna Goracci, Chiara Fallerini, Alessandra Renieri, Jean-Laurent Casanova, Yuval Itan, Cem E. Atbaşoğlu, Meram C. Saka, İ. Halil Kavaklı, and Tayfun Özçelik. Human cry1 variants associate with attention deficit/hyperactivity disorder. The Journal of clinical investigation, 130:3885-3900, Jun 2023. URL: https://doi.org/10.1172/jci135500, doi:10.1172/jci135500. This article has 48 citations.

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  13. (onat2023humancry1variants pages 5-9): O. Emre Onat, M. Ece Kars, Şeref Gül, Kaya Bilguvar, Yiming Wu, Ayşe Özhan, Cihan Aydın, A. Nazlı Başak, M. Allegra Trusso, Arianna Goracci, Chiara Fallerini, Alessandra Renieri, Jean-Laurent Casanova, Yuval Itan, Cem E. Atbaşoğlu, Meram C. Saka, İ. Halil Kavaklı, and Tayfun Özçelik. Human cry1 variants associate with attention deficit/hyperactivity disorder. The Journal of clinical investigation, 130:3885-3900, Jun 2023. URL: https://doi.org/10.1172/jci135500, doi:10.1172/jci135500. This article has 48 citations.

  14. (onat2023humancry1variants pages 9-10): O. Emre Onat, M. Ece Kars, Şeref Gül, Kaya Bilguvar, Yiming Wu, Ayşe Özhan, Cihan Aydın, A. Nazlı Başak, M. Allegra Trusso, Arianna Goracci, Chiara Fallerini, Alessandra Renieri, Jean-Laurent Casanova, Yuval Itan, Cem E. Atbaşoğlu, Meram C. Saka, İ. Halil Kavaklı, and Tayfun Özçelik. Human cry1 variants associate with attention deficit/hyperactivity disorder. The Journal of clinical investigation, 130:3885-3900, Jun 2023. URL: https://doi.org/10.1172/jci135500, doi:10.1172/jci135500. This article has 48 citations.

  15. (wu2023updatesandconfounding pages 6-7): Alexandra Wu. Updates and confounding factors in delayed sleep–wake phase disorder. Sleep and Biological Rhythms, 21:279-287, Mar 2023. URL: https://doi.org/10.1007/s41105-023-00454-4, doi:10.1007/s41105-023-00454-4. This article has 7 citations and is from a peer-reviewed journal.

  16. (NCT03715465 chunk 1): Leslie Swanson. The Clinical Utility of Measuring the Circadian Clock in Treatment of Delayed Sleep-Wake Phase Disorder. University of Michigan. 2019. ClinicalTrials.gov Identifier: NCT03715465

  17. (smieszek2023casereporta pages 1-2): Sandra P. Smieszek, Alyssa R. Kaden, Caroline E. Johnson, Jennifer L. Brzezynski, Changfu Xiao, Christos M. Polymeropoulos, Gunther Birznieks, Helene A. Emsellem, and Mihael H. Polymeropoulos. Case report: a patient with delayed sleep-wake phase disorder and optic nerve hypoplasia treated with tasimelteon: a case study. Frontiers in Neuroscience, Nov 2023. URL: https://doi.org/10.3389/fnins.2023.1287514, doi:10.3389/fnins.2023.1287514. This article has 0 citations and is from a peer-reviewed journal.

  18. (wu2023updatesandconfounding pages 8-9): Alexandra Wu. Updates and confounding factors in delayed sleep–wake phase disorder. Sleep and Biological Rhythms, 21:279-287, Mar 2023. URL: https://doi.org/10.1007/s41105-023-00454-4, doi:10.1007/s41105-023-00454-4. This article has 7 citations and is from a peer-reviewed journal.

  19. (hartstein2024differencesinthe pages 1-2): Lauren E. Hartstein, Monique K. LeBourgeois, Mark T. Durniak, and Raymond P. Najjar. Differences in the pupillary responses to evening light between children and adolescents. Journal of Physiological Anthropology, Jul 2024. URL: https://doi.org/10.1186/s40101-024-00363-6, doi:10.1186/s40101-024-00363-6. This article has 10 citations and is from a peer-reviewed journal.

  20. (schollhorn2024theimpactof pages 1-2): Isabel Schöllhorn, Oliver Stefani, Robert J. Lucas, Manuel Spitschan, Christian Epple, and Christian Cajochen. The impact of pupil constriction on the relationship between melanopic edi and melatonin suppression in young adult males. Journal of Biological Rhythms, 39:282-294, Feb 2024. URL: https://doi.org/10.1177/07487304241226466, doi:10.1177/07487304241226466. This article has 11 citations and is from a peer-reviewed journal.

  21. (smieszek2023casereporta pages 5-5): Sandra P. Smieszek, Alyssa R. Kaden, Caroline E. Johnson, Jennifer L. Brzezynski, Changfu Xiao, Christos M. Polymeropoulos, Gunther Birznieks, Helene A. Emsellem, and Mihael H. Polymeropoulos. Case report: a patient with delayed sleep-wake phase disorder and optic nerve hypoplasia treated with tasimelteon: a case study. Frontiers in Neuroscience, Nov 2023. URL: https://doi.org/10.3389/fnins.2023.1287514, doi:10.3389/fnins.2023.1287514. This article has 0 citations and is from a peer-reviewed journal.

  22. (feder2024justletme pages 7-9): Michael A. Feder and Argelinda Baroni. Just let me sleep in: identifying and treating delayed sleep phase disorder in adolescents. Child and adolescent psychiatric clinics of North America, 30 1:159-174, Jan 2024. URL: https://doi.org/10.1016/j.chc.2020.08.005, doi:10.1016/j.chc.2020.08.005. This article has 19 citations and is from a peer-reviewed journal.

  23. (consens2023circadianrhythmsleepwake pages 150-152): Flavia B. Consens. Circadian rhythm sleep-wake disorders. CONTINUUM: Lifelong Learning in Neurology, 29:1149-1166, Aug 2023. URL: https://doi.org/10.1212/con.0000000000001287, doi:10.1212/con.0000000000001287. This article has 7 citations.

  24. (NCT04652882 chunk 1): Evaluating the Effects of Tasimelteon vs. Placebo in Delayed Sleep-Wake Phase Disorder (DSWPD). Vanda Pharmaceuticals. 2020. ClinicalTrials.gov Identifier: NCT04652882

  25. (NCT06701396 chunk 1): Evaluating the Effects of Tasimelteon Vs. Placebo in Delayed Sleep-Wake Phase Disorder (DSWPD) and the CRY1Δ11 Variant. Vanda Pharmaceuticals. 2024. ClinicalTrials.gov Identifier: NCT06701396