Delayed Sleep Phase Disorder
(Delayed Sleep Phase Syndrome)
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What Is Delayed Sleep Phase Disorder?
Imagine feeling wide awake at 2 AM when the rest of the world is sound asleep, only to struggle to wake up when everyone else gets up, or feel like you’re in a half-asleep fog during morning meetings or classes. For those with delayed sleep-wake phase disorder (DSWPD) (commonly known as delayed sleep phase disorder or DSPD), this is not just an occasional occurrence. It’s a persistent pattern that reflects an underlying sleep disorder. And this pattern of delayed sleep and wake times can lead to chronic sleep deprivation and associated consequences at school or work.
DSWPD is the most common condition in a group of sleep disorders known as circadian rhythm sleep-wake disorder (or circadian rhythm sleep disorders). It’s characterised by a significant delay in sleep onset and wake times that are out of alignment with societal norms (American Academy of Sleep Medicine, 2014). It’s not laziness. It’s a chronic condition related to the body’s internal clock and can have profound impacts on an individual's daily functioning, mental health, and overall quality of life.
Prevalence of Delayed Sleep-Wake Phase Sleep Disorder
Delayed sleep-wake phase disorder (DSWPD) is the most common circadian rhythm sleep-wake disorder, however its exact prevalence remains uncertain. Estimates of DSWPD prevalence vary widely, ranging from 0.2% to 10% depending on the diagnostic sample and methodology used, with younger population samples typically showing higher rates (Micic et al., 2016).
Demographic Patterns
While DSWPD can affect individuals across the lifespan, several key demographic patterns have emerged from epidemiological (public health) research:
Age Distribution: DSWPD shows a clear prevalence for adolescents and young adults. The onset of DSWPD symptoms often coincides with puberty, a period marked by significant changes in sleep physiology and circadian rhythms (Richardson et al., 2017).
Adolescent Prevalence: The high prevalence among adolescents is particularly concerning. Data from the Centers for Disease Control and Prevention (CDC) indicate that 70% of adolescents report insufficient sleep on school nights, a pattern that may be partly attributable to DSWPD in some cases (Eaton et al., 2010). A large-scale study conducted in Norway found that approximately 3.3% of adolescents met the diagnostic criteria for DSWPD (Saxvig et al., 2012)
Gender Distribution: Interestingly, studies have consistently found no significant gender differences in DSWPD prevalence. This suggests that biological sex may not be a major risk factor for developing the disorder (Micic et al., 2016).
Geographic and Cultural Variations
The prevalence of DSWPD appears to vary across different countries and cultures, although more research is needed to fully understand these differences. Factors such as societal norms around when individuals go to sleep, school and work schedules, and exposure to natural light may contribute to these variations.
Causes and Risk Factors of Delayed Sleep Phase Disorder
Delayed Sleep-Wake Phase Disorder (DSWPD) arises from a complex interaction of biological, environmental, and behavioral factors that influence fall asleep and wake times. At present, these underlying mechanisms are not fully understood, however some factors have been identified.
Circadian Rhythm Disruptions
Circadian Phase Delay
A primary cause of DSWPD is a significant delay in the individual's circadian rhythm (governed by an internal clock in the human brain). This delay is evidenced by later timing of physiological markers such as dim light melatonin onset (DLMO) and core body temperature minimum (Tmin) (Micic et al., 2016). For instance, one study found that subjects with DSWPD reached Tmin at 7:17 A.M. ± 47 minutes, compared to 4:56 A.M. ± 19 minutes in control subjects (Ozaki et al., 1996).
Longer Circadian Period
Many individuals with DSWPD have an endogenous (naturally occurring) circadian period or length (known as “tau”) that is longer than 24 hours. This can range from slightly over 24 hours to as long as 24.64 hours (Micic et al., 2016). This extended internal day length requires larger daily adjustments to maintain synchronization with the external environment. When these adjustments are incomplete, it can lead to a progressive delay in usual sleep and wake timing.
Altered Light Sensitivity
Hypersensitivity to Evening Light
Studies have suggested that individuals with DSWPD may be more sensitive to the phase-delaying effects of light exposure in the evening. This heightened sensitivity to light can magnify circadian delays, pushing the time an individual falls asleep later (unable to fall asleep) leading and individual to sleep later, making it more challenging to maintain a conventional sleep schedule (Aoki et al., 2001).
Reduced Morning Light Sensitivity
Some research indicates that people with DSWPD may be less responsive to the phase-advancing effects of morning light that bring forward the time to wake up, and support waking earlier in the morning and earlier times to fall asleep in the evening. This diminished sensitivity could impair the natural resetting of the circadian system that typically occurs with early light exposure (Micic et al., 2016).
Homeostatic Sleep Drive Alterations
The homeostatic sleep drive, which builds up during wakefulness and dissipates during sleep, may function differently in people with delayed sleep phase syndrome. Some studies suggest that:
Homeostatic sleep pressure accumulates more slowly during wakefulness in DSWPD patients (Duffy et al., 2001).
The dissipation of sleep pressure during sleep may also occur at a slower rate (Uchiyama et al., 1999).
These alterations in homeostatic sleep regulation could contribute to the delayed sleep patterns characteristic of DSWPD.
Genetic Factors
Several genetic polymorphisms have been associated with an increased risk of developing DSWPD:
Variations in the human Period 3 (hPER3) gene (Jones et al., 2013)
Polymorphisms in hPER1 and hPER2 genes (Carpen et al., 2006; Carpen et al., 2005)
Mutations in the CLOCK gene (Katzenberg et al., 1998)
Environmental and Behavioral Risk Factors
Reduced Exposure to Natural Light
The widespread use of artificial lighting and increased time spent indoors have diminished exposure to natural light cycles. This reduction in environmental zeitgebers (“time giving signals” to the internal master circadian clock) can weaken the entrainment of the circadian system, potentially increasing susceptibility to DSWPD (Wright et al., 2013).
Evening Technology Use
The prevalence of light-emitting electronic devices has introduced a new risk factor for circadian disruption. Evening exposure to blue light from screens can suppress melatonin production and delay sleep onset in those with more sensitive eyes exacerbating DSWPD symptoms (Micic et al., 2016).
Personality Traits
Certain personality characteristics may predispose individuals to DSWPD. A study by Micic et al. (2017) found that individuals with DSWPD reported higher neuroticism (emotional sensitivity) and significantly lower extraversion, conscientiousness, and agreeableness compared to healthy sleepers. These traits may influence behaviors around sleep routine, contributing to delayed sleep patterns.
Developmental Factors
Adolescence is a period of heightened risk for DSWPD due to several factors:
Puberty-related changes in the circadian system lead to a natural delay in sleep timing (Richardson et al., 2017).
The homeostatic sleep drive accumulates more slowly in adolescents, potentially contributing to later bedtimes (Campbell et al., 2011).
Social and academic pressures may encourage later sleep times, and poor sleep habits, reinforcing delayed patterns.
Symptoms and Diagnosis of Delayed Sleep-Wake Phase Disorder
Clinical Presentation
Delayed Sleep-Wake Phase Disorder (DSWPD) is characterized by a persistent pattern of sleep-wake timing that is significantly delayed relative to conventional or desired fall asleep and wake times. The primary symptoms include:
Difficulty falling asleep at socially acceptable bedtimes (falling asleep 2am or later is common)
Inability to wake up at desired times for work, school, or other obligations (waking 9am or later is common)
Excessive daytime sleepiness, particularly in the morning hours (or feeling like one is in a “fog”)
Normal sleep quality and duration when allowed to follow preferred sleep schedule (this may be most obvious on weekends or during holiday periods)
Individuals with DSWPD typically report feeling most alert and productive in the evening hours, displaying a strong preference for "eveningness" (Gradisar et al., 2011). When attempting to adhere to conventional schedules, these individuals often experience chronic insufficient sleep, leading to significant impairment of daytime functioning.
Diagnostic Criteria
According to the International Classification of Sleep Disorders, 3rd Edition (ICSD-3), the diagnosis of DSWPD requires the following criteria to be met:
A significant delay in the major sleep episode relative to desired or required sleep and wake-up times
Symptoms present for at least 3 months
Improved sleep quality and duration when following preferred sleep schedule
Sleep diary or actigraphy data demonstrating a delay in sleep-wake timing for at least 7-14 days
Sleep disturbance not better explained by another sleep disorder (such as chronic insomnia disorder, or sleep apnea), medical condition, or substance use
Diagnostic Procedures
Sleep History
A comprehensive sleep history is crucial for diagnosing DSWPD. Clinicians should inquire about:
Typical sleep and wake times on both work/school days and free days
Difficulty falling asleep or waking at desired times
Daytime sleepiness and its impact on daily functioning
Evening activities and light exposure patterns
Sleep Diary and Actigraphy
Quantitative data on sleep-wake patterns are essential for diagnosis. A sleep study is not typically required. Instead, patients are typically asked to keep a sleep diary (aka sleep log) for 1-2 weeks to provide insight into sleep cycles. When available, actigraphy can provide objective data on sleep-wake cycles and sleep periods, offering valuable insights for patients who may struggle with self-reporting (American Academy of Sleep Medicine, 2014).
Chronotype Questionnaires
Self-administered questionnaires can help differentiate DSWPD from other common sleep disorders. Tools include:
Horne-Östberg Morningness-Eveningness Questionnaire
Munich ChronoType Questionnaire
Children's Chronotype Questionnaire (for ages 4-11)
These assessments provide information on an individual's circadian preference and can correlate with objective measures of circadian phase (Baehr et al., 2000).
Circadian Phase Markers
While not typically used in clinical practice, research settings may employ biological markers to assess circadian timing:
Dim Light Melatonin Onset (DLMO): Measures the timing of melatonin secretion under controlled light conditions
Core Body Temperature Minimum (Tmin): Identifies the lowest point in the circadian rhythm of core body temperature
These markers can provide precise information about an individual's circadian phase but are typically not necessary for clinical diagnosis (Lack & Wright, 2007).
Differential Diagnosis
It is crucial to distinguish DSWPD from other conditions that may present with similar symptoms as incorrect treatment will not only be ineffective, but can have a significant negative impact (.e.g., insomnia treatments such as CBTi can be harmful under certain circumstances).
Insomnia: Individuals with insomnia struggle to initiate or maintain sleep even when following their preferred sleep schedule. Individuals with DSPD often sleep well when they go to bed on their preferred sleep schedule.
Depression and Anxiety: While often co-occurring with DSWPD, these conditions can independently cause sleep disturbances and should be carefully evaluated.
Attention-Deficit Hyperactivity Disorder (ADHD): The cognitive and behavioral consequences of DSWPD can mimic ADHD symptoms, necessitating careful assessment to avoid misdiagnosis (Wilhelmsen-Langeland et al., 2019).
A comprehensive approach to assessment that employs a combination of clinical history, objective sleep data, and standardized assessments ensures accurate diagnosis. This in turn supports patients receiving appropriate treatment tailored to their specific needs and challenges.
Complications of Delayed Sleep-Wake Phase Disorder
Delayed Sleep-Wake Phase Disorder (DSWPD) is often associated with various co-occurring conditions and can lead to significant complications if left untreated. Being able to address associated conditions is crucial for comprehensive patient care and effective management strategies.
Comorbid Mental Health Conditions
Depression and Anxiety
DSWPD frequently co-occurs with mood disorders, particularly depression and anxiety. A Norwegian population-based study found that adolescents with DSWPD were more likely to experience symptoms of depression and anxiety compared to their peers without sleep phase delays (Sivertsen et al., 2015). The relationship between DSWPD and mood disorders is likely bidirectional, with each condition potentially exacerbating the other.
Attention-Deficit/Hyperactivity Disorder (ADHD)
There is a notable association between DSWPD and ADHD, particularly in adolescents and young adults. The symptoms of chronic sleep deprivation resulting from DSWPD can mimic those of ADHD, leading to potential misdiagnosis (Wilhelmsen-Langeland et al., 2019). Conversely, individuals with ADHD may be more prone to developing delayed sleep patterns due to difficulties with time management and impulse control.
Cognitive Impairments
Executive Functioning Deficits
DSWPD is associated with negative cognitive outcomes, particularly in the domains of executive functioning. Research has shown that individuals with DSWPD may experience:
Reduced working memory capacity
Impaired attention and concentration
Difficulties with treatment adherence
These cognitive impairments are likely mediated by chronic insufficient sleep and circadian misalignment (Wilhelmsen-Langeland et al., 2019).
Physical Health Complications
While the direct physical health complications of DSWPD are less extensively studied than its mental health and cognitive impacts, chronic circadian misalignment and sleep deprivation can contribute to various health issues:
Metabolic Disturbances
Chronic sleep deprivation and circadian misalignment have been associated with:
Increased risk of obesity
Impaired glucose tolerance
Higher risk of developing type 2 diabetes
Cardiovascular Risk
Long-term circadian disruption may contribute to:
Elevated blood pressure
Increased risk of cardiovascular disease
Gastrointestinal Issues
Some individuals with DSWPD may experience:
Altered appetite patterns
Digestive discomfort due to eating at atypical times
Social and Interpersonal Complications
The misalignment between an individual's sleep-wake schedule and societal norms can lead to significant social challenges:
Difficulty maintaining relationships due to conflicting schedules
Social isolation or reduced participation in morning activities
Strain on family dynamics, particularly in households with children or early-rising partners
Increased Risk of Substance Use
Individuals with DSWPD may be at higher risk for substance use, potentially as a means of managing their sleep difficulties or coping with associated stress:
Higher rates of caffeine consumption to combat daytime sleepiness
Increased likelihood of alcohol use to facilitate sleep onset
Potential misuse of sleep medications or stimulants
Impact and Burden of Delayed Sleep-Wake Phase Disorder
Delayed Sleep-Wake Phase Disorder (DSWPD) can have significant impacts on individuals and society, affecting various aspects of daily life, mental health, and economic productivity.
Individual Impact
The most immediate impact of DSWPD is on an individual's daily functioning and quality of life. Chronic sleep insufficiency resulting from the disorder can lead to excessive daytime sleepiness, fatigue, and impaired cognitive performance (Wilhelmsen-Langeland et al., 2019). This can significantly affect academic and occupational performance, potentially leading to decreased productivity, increased absenteeism, and even job loss or academic failure.
Individuals with DSWPD often experience difficulties in maintaining social relationships due to their misaligned sleep schedule. The inability to participate in morning activities or early social events can lead to feelings of isolation and social disconnection (Micic et al., 2016). This social impairment can contribute to the development or exacerbation of mental health issues, such as depression and anxiety, which are common comorbidities in DSWPD (Sivertsen et al., 2015).
The chronic stress of trying to conform to societal norms while battling against one's internal circadian rhythm can also lead to decreased self-esteem and overall life satisfaction. This constant struggle can create a cycle of poor sleep, daytime impairment, and psychological distress, significantly impacting an individual's overall well-being and quality of life.
Societal & Economic Impact
The societal burden of DSWPD extends beyond the individual level, affecting various sectors of society. In the educational sector, DSWPD can contribute to increased rates of truancy, absenteeism, and potentially higher dropout rates among students, particularly adolescents and young adults who are most susceptible to the disorder (Saxvig et al., 2012). This can lead to long-term consequences for educational attainment and future career prospects.
In the workplace, DSWPD can result in decreased productivity, increased absenteeism, and higher rates of workplace accidents due to fatigue and impaired cognitive functioning. A study by Kessler et al. (2011) estimated that insomnia, which shares some similarities with DSWPD in terms of sleep insufficiency, was associated with 11.3 days of lost work performance per year for each worker with insomnia. While this study did not specifically focus on DSWPD, it suggests the potential magnitude of workplace productivity losses associated with sleep disorders.
The healthcare system also bears a significant burden from DSWPD and its associated comorbidities. Individuals with DSWPD may require more frequent medical consultations, mental health services, and potentially medication for associated conditions such as depression or anxiety. The long-term health consequences of chronic circadian misalignment and sleep insufficiency, such as increased risk of obesity, type 2 diabetes, and cardiovascular disease, can further strain healthcare resources (Knutson & von Schantz, 2018).
While specific economic data on DSWPD is limited, the overall economic impact of sleep disorders is substantial. A report by the RAND Corporation estimated that insufficient sleep costs the U.S. economy up to $411 billion annually, equivalent to 2.28% of its GDP (Hafner et al., 2017). Although this figure encompasses all forms of insufficient sleep, it underscores the potential economic implications of disorders like DSWPD that contribute to chronic sleep insufficiency.
Treatment For DSPD
The treatment of Delayed Sleep-Wake Phase Disorder (DSWPD) aims to realign the patient's circadian rhythm with desired sleep-wake times and improve daytime functioning. A multi-faceted approach is often necessary, combining behavioral interventions, light therapy, and, in some cases, pharmacological treatments.
Behavioral Modifications
Sleep Hygiene and Scheduling
Improving sleep hygiene where required, especially establishing consistent sleep-wake schedules is fundamental to DSWPD management:
Patients should be encouraged to adhere to a regular sleep schedule of fixed sleep-wake timings, even on weekends and holidays.
Daytime naps should be avoided to prevent interference with nighttime sleep (Auger et al., 2015).
Sharkey et al. (2011) demonstrated that strict adherence to a fixed earlier sleep-wake schedule could significantly advance salivary DLMO in individuals with subclinical DSWPD.
Lifestyle Adjustments
Moderate or eliminate caffeine, alcohol, nicotine and cannabis use, especially in the evening hours.
Light Therapy
Light is the most potent zeitgeber or time-giving signal to the master circadian clock in the human brain and can contribute to therapy for DSWPD. This can be through a light box, light glasses, or regular exposure to natural sunlight.
Chronotherapy
This approach is less frequently used. Chronotherapy involves progressively delaying bedtime by 1–3 hours on successive days to reset the circadian clock. However, it can be disruptive to the individual's normal schedule and is not as commonly employed as bright light therapy (Lack & Wright, 2007).
Melatonin
Melatonin administration can be effective in phase-advancing circadian rhythms when timed correctly. Correct type of melatonin supplement and timing of administration is important for effectiveness and can be challenging without accurate information about endogenous melatonin production and clinical experience.
Pharmacological Treatment
The use of hypnotic medications in DSWPD treatment is limited by a lack of supporting data and is generally discouraged (American Academy of Sleep Medicine, 2014).
Cognitive-Behavioral Therapy For Insomnia (CBTi)
For patients with comorbid insomnia or anxiety related to sleep onset delays, careful application of cognitive-behavioral therapy for insomnia (CBT-I) can be beneficial:
CBT-I can address maladaptive thoughts and behaviors that may perpetuate sleep disturbances.
A meta-analysis by Gee et al. (2019) found that nonpharmacological sleep interventions, including CBTi, were effective in reducing depressive symptoms in individuals with sleep difficulties.
Addressing Co-occurring Conditions
Given the high prevalence of co-occurring mental health conditions in DSWPD, a comprehensive treatment approach should include:
Screening and treatment for depression, anxiety, and ADHD when present.
Collaborative care between sleep specialists and mental health professionals to address both circadian and psychiatric symptoms concurrently.
Tailoring Treatment to Individual Needs
The wide range of ages and work/life situations of DSWPD presentations means that individualized treatment plans are critical. These must consider the patient's age, lifestyle, work/school obligations, and comorbid conditions when designing interventions. It’s also important that there’s regular follow-up and adjustment of treatment strategies based on patient response and adherence.
Clinical Comments
Delayed Sleep-Wake Phase Disorder (DSWPD) is a complex circadian rhythm disorder with significant impacts on health, wellbeing and general quality of life. After insomnia, it is the most common condition we treat at The Better Sleep Clinic.
On paper, treatment looks straightforward, however, because this condition comes with a range of mental health complications including substance misuse problems (it's common for people with DSPD to “self-medicate” with alcohol or cannabis) it can be a challenging condition to both diagnose and to successfully manage.
Written By: The Better Sleep Clinic Team
Reviewed By: Dan Ford, Sleep Psychologist
Frequently Asked Questions About Delayed Sleep-Wake Phase Disorder (DSWPD)
What is Delayed Sleep-Wake Phase Disorder (DSWPD)?
Delayed Sleep-Wake Phase Disorder (DSWPD) is a circadian rhythm sleep-wake disorder characterized by a persistent delay in sleep onset and wake times. Individuals with DSWPD struggle to fall asleep at conventional bedtimes and have difficulty waking up at times required for work, school, or other daytime commitments.
How common is DSWPD?
The prevalence of DSWPD varies widely, ranging from 0.2% to 10% of the general population, depending on the study methodology and population examined. It is more common among adolescents and young adults, with some studies reporting prevalence rates of up to 3.3% in this age group.
What are the main symptoms of DSWPD?
The primary symptoms of DSWPD include:
Chronic difficulty falling asleep at conventional bedtimes
Extreme difficulty awakening at desired times
Normal sleep quality and duration when allowed to follow preferred schedule
Daytime sleepiness and impaired functioning
Evening alertness and productivity
What causes DSWPD?
DSWPD arises from a complex interplay of factors, including:
Circadian phase delay
Longer intrinsic circadian period
Differences in homeostatic sleep drive
Altered sensitivity to light
Genetic predisposition
Behavioral and environmental factors
Age and developmental changes, particularly during adolescence
How is DSWPD diagnosed?
DSWPD is typically diagnosed through:
Clinical interview and sleep history
Sleep diary documentation
Actigraphy (when available)
Chronotype questionnaires
Dim Light Melatonin Onset (DLMO) testing (in some cases)
Polysomnography (not common, only to rule out other sleep disorders)
What are the potential complications of untreated DSWPD?
Untreated DSWPD can lead to various complications, including:
Mental health issues (e.g., depression, anxiety)
Cognitive and academic difficulties
Occupational problems
Social isolation
Increased risk of metabolic and cardiovascular disorders
How is DSWPD treated?
Treatment for DSWPD typically involves a combination of:
Behavioral modifications (e.g., sleep hygiene, gradual sleep schedule adjustment)
Light therapy (morning bright light exposure and evening light avoidance)
Chronotherapy (in some cases)
Pharmacological interventions (e.g., melatonin)
Management of comorbid conditions
Can DSWPD be cured?
While DSWPD cannot be "cured" in the traditional sense, it can be effectively managed with appropriate treatment. Many individuals with DSWPD can significantly improve their sleep patterns and quality of life through a combination of behavioral interventions, light therapy, and, when necessary, medication.
Is DSWPD the same as being a "night owl"?
While both DSWPD and being a "night owl" involve a preference for later sleep times, DSWPD is a clinical disorder that causes significant distress or impairment in daily functioning. Unlike a simple preference for later hours, DSWPD involves a persistent misalignment between an individual's circadian rhythm and societal expectations.
Can lifestyle changes alone treat DSWPD?
For some individuals with mild DSWPD, lifestyle changes such as maintaining consistent sleep schedules, practicing good sleep hygiene, and managing light exposure may be sufficient. However, many people with DSWPD require a more comprehensive treatment approach, including light therapy and possibly medication, under the guidance of a sleep specialist.
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