Delayed sleep-wake phase disorder
Delayed sleep–wake phase disorder is a circadian rhythm disorder in which sleep onset is persistently at least 2 hours later than desired, resulting in reduced sleep time, trouble waking when required, and daytime sleepiness and dysfunction. As such, the disorder can be misdiagnosed as initial insomnia. People with late chronotypes (‘night owls’) who do not experience daytime sequelae are not considered to have delayed sleep–wake phase disorder.
Delayed sleep–wake phase disorder affects 2 to 8% of the population and is most prevalent among young adults and adolescents—pubertal development causes a natural phase delay. People with delayed sleep–wake phase disorder often have comorbid psychiatric disorders (eg depression, substance abuse, anxiety) or psychosocial problems.
If a persistent delay in sleep onset causes daytime sleepiness and dysfunction, treat delayed sleep–wake phase disorder by encouraging good sleep practices and, use the following steps to slowly adjust the circadian rhythm to a sleep–wake routine that provides sufficient sleep:
- increase sleep efficiency (ratio of time asleep to time in bed) by restricting time in bed to times identified from the sleep diary or actigraphy for several days (eg a person who naturally sleeps from 1.00 to 8.00 am would start going to bed and getting up at these times)
- shift bedtime and wake-up time earlier by 15 to 30 minutes—to assist sleep–wake shift, reduce exposure to light in late afternoon and evening (eg if outside, wear sunglasses) and seek exposure to bright natural or artificial light for at least 30 minutes upon waking in the morning
- once the person sleeps well in the new schedule (ie time in bed approximates time asleep), continue to shift bedtime and wake-up times earlier by 15 to 30 minutes increments until desired sleep–wake routine is achieved.
For adults with delayed sleep–wake phase disorder, combining the practices above with immediate-release melatonin can improve sleep duration, assist phase shift and reduce daytime sequelae1. A reasonable regimen is:
melatonin immediate-release 0.5 to 5 mg orally, 1 hour before desired bedtime. Review within 4 weeks; the optimal duration of therapy is unknown23. delayed sleep–wake phase disorder melatonin melatonin melatonin
Avoid internet-sourced melatonin formulations because the melatonin content in these preparations is unreliable.
Once the desired sleep–wake routine is achieved, advise the patient to maintain it by continuing good sleep practices.
If the above recommendations are not successful, refer the patient to a sleep expert, and in the case of children, a paediatrician.