Description: Delayed sleep-wake phase disorder (DSWPD) is a circadian rhythm sleep-wake disorder characterised by late bedtime and waking on most days with delay of usually > 2 hours in relation to conventional or desired times.
Prevalence: Its prevalence is unknown in the general population but is highest in adolescents and young adults (7%-16% reported prevalence). Circadian rhythm is chronically and persistently delayed due to genetic, biological, and/or psychosocial factors.
Risk factors:
- age (highest in adolescents and young adults) (7%-16% reported prevalence)
- environmental factors, including: reduced light exposure in morning, excessive light exposure in evening
- shift work
- travel with time zone changes
Behavioural factors:
- excessive intake of caffeine or other stimulants
- school avoidance
- family dysfunction
- social maladjustment
- personal, social, and occupational activities that continue late into the evening
- medical conditions, including traumatic brain injury causing disruption of circadian rhythm systems
Associated conditions
- insomnia
- psychiatric disorders (such as substance abuse, mood disorders [such as bipolar disorder] or anxiety)
- non-24-hour sleep-wake disorder
- seasonal affective disorder
- obsessive compulsive disorder
- attention deficit hyperactivity disorder
- autism spectrum disorders
Evaluation:
International Classification of Sleep Disorders – Third Edition diagnostic criteria includes all of the following:
- presence of significant delay in falling asleep and waking up on desired schedule as reported by patient or caregiver
- presence of symptoms for ≥ 3 months
- improvement of sleep quality and duration with delayed timing of sleep when patient chooses schedule
- confirmation of delay in sleep period by ≥ 7 day (preferably ≥ 14 day) sleep log, and, if possible, actigraphy monitoring; including work/school days and free days
- sleep disturbance not better explained by: another current sleep disorder, medical or neurological disorder, mental disorder, medication use, and substance use disorder
Testing overview
- sleep logs and/or actigraphy evaluating sleep schedules over ≥ 7 consecutive days (preferably ≥ 14 days) are primary diagnostic tool
- standardized chronotype questionnaires suggested to assess morningness or eveningness preference
- polysomnography not routinely indicated or required for diagnosis, but may be useful to exclude other sleep disorders when suspected
- circadian phase markers (such as dim light melatonin onset) not routinely suggested but may be useful for determining the optimal timing of treatment
Management
- Advise all patients on general sleep hygiene measures.
- The usual treatment involves altering entraining signals and maintaining regular sleep-wake times.
- Chronotherapy involves incrementally delaying the sleep schedule until the desired sleep schedule is reached.
- Strategically timed melatonin is suggested in most patients
- Light therapy: involves a combination of bright light upon awakening and evening light restriction
- Combination therapy is often employed and involves bright light plus melatonin, sleep scheduling, or cognitive behavioural therapy.
References
National Library of Medicine, or “Vancouver style” (International Committee of Medical Journal Editors):
- DynaMed Plus [Internet]. Ipswich (MA): EBSCO Information Services. 1995 – . Record No. 114220, Delayed sleep-wake phase disorder; [updated 2017 Oct 03, Brisbane Australia 15/05/2018. Available from http://www.dynamed.com/login.aspx?direct=true&site=DynaMed&id=114220.
