Delayed Sleep-Wake Phase Disorder: when being a Night Owl becomes a sleep problem

If you naturally drift towards a 2am bedtime and struggle to wake in the morning, you might assume you're simply a night owl.

It's true - you might be! A naturally late chronotype doesn't mean that you have a sleep disorder, but when your sleep timing is persistently much later than the schedule you need or want to follow — making it difficult to fall asleep earlier and extremely difficult to wake on time — you could be experiencing Delayed Sleep-Wake Phase Disorder (DSWPD).

A 2026 review of Delayed Sleep-Wake Phase Disorder highlights an interesting development in how scientists are thinking about the condition: two people can have an almost identical pattern of very late sleep, but the mechanisms keeping their sleep late may be quite different. That could matter for treatment.

What is Delayed Sleep-Wake Phase Disorder (DSWPD)?

DSWPD is a circadian rhythm sleep-wake disorder in which sleep and wake times are persistently delayed relative to the times someone needs or wants to sleep.

Someone might, for example, struggle to fall asleep until 2am or 3am and find getting up at 7am extraordinarily difficult.

This can look like insomnia, but there's an important clue: when people with DSWPD are allowed to follow their preferred schedule, they can often fall asleep more easily and sleep relatively normally. The problem isn't necessarily an inability to sleep. It's an inability to sleep at the required time.

What's the difference between being a night owl and having DSWPD?

Not everyone who likes staying up late has a sleep disorder. DSWPD causes significant problems because someone's sleep timing conflicts with the demands of school, work or everyday life.

If your body isn't ready for sleep until 2am but your alarm goes off at 6.30am, the result can be chronic sleep deprivation, severe difficulty waking, daytime sleepiness, problems concentrating, lateness or absence from school or work, and considerable frustration around sleep.

DSWPD is particularly associated with adolescence and young adulthood. Estimates vary depending on the population and diagnostic criteria, but large studies have found DSWPD in around 3% of adolescents and a similar proportion of young adults.

Sleep timing naturally shifts later during adolescence, reflecting changes in both the circadian system and the build-up of sleep pressure. Evening light, phones, gaming, socialising, homework and greater independence over bedtime can push timing later still.

Most teenagers who prefer late nights don't have DSWPD. The important question is whether the delay is persistent and interfering with someone's ability to function and get enough sleep.

What causes Delayed Sleep-Wake Phase Disorder?

Traditionally, DSWPD has largely been thought of as a problem with the internal biological clock. For some people, that certainly seems to be true: biological markers of circadian timing, including the evening rise in melatonin, occur significantly later than usual.

A new 2026 review highlights evidence that DSWPD may be more complicated. Some people who consistently sleep very late appear to have relatively normal circadian timing. In these cases, sleep behaviour is delayed more than the biological clock itself.

Why might that happen?

Perhaps the evening is the first time you feel free from demands. Maybe you become absorbed in work, gaming or scrolling. Perhaps staying up late has become associated with productivity, autonomy or calm. Alternatively, attempts to force an earlier bedtime may have resulted in hours spent awake, frustrated and increasingly anxious about sleep.

This doesn't mean someone is “just choosing to stay up late”. Biology, psychology, behaviour and environment can all interact to make a delayed sleep schedule surprisingly persistent.

For many people, it's probably a combination.

DSWPD also commonly overlaps with conditions including anxiety, depression, ADHD and autism, as well as other sleep disorders. This reinforces the importance of looking at the whole person rather than assuming that every late sleeper has the same underlying problem.

How can you shift a delayed body clock earlier?

The right approach depends partly on what's keeping your sleep late.

Get plenty of morning light

Light is the most powerful environmental signal to the circadian clock. Bright light during the biological morning can advance circadian timing, gradually helping sleep and wake times move earlier. Getting outdoors relatively soon after waking — perhaps by walking, exercising or eating breakfast outside — is a simple way of increasing morning light exposure.

Reduce bright light in the late evening

Light later in the evening can push circadian timing in the opposite direction. You don't need to spend your evening sitting in darkness, but if you're trying to move your sleep earlier, consider lowering indoor lighting and reducing prolonged exposure to very bright screens close to your face. The aim is to create a strong contrast between bright, active days and darker, calmer evenings.

Keep your wake-up time reasonably consistent

Large swings between early weekday alarms and very late weekend lie-ins can make it harder to stabilise a delayed sleep-wake rhythm. A reasonably consistent wake time, combined with morning light, can provide a strong daily timing signal.

Use activity and meals as daytime signals

Regular daytime exercise, meals at broadly consistent times and being physically and socially active during the day can provide additional cues that reinforce the distinction between day and night.

Look at what's keeping you awake in the evening

If behaviour is contributing to your late sleep, light exposure alone may not solve the problem. Are you losing track of time online? Does work expand into the evening? Is nighttime your only opportunity to be alone? Or are you going to bed long before you're sleepy and then spending hours awake? Behavioural approaches, including sleep scheduling and elements of Cognitive Behavioural Therapy for Insomnia (CBT-I), may be helpful when these patterns are part of the problem.

Can melatonin help Delayed Sleep-Wake Phase Disorder?

Melatonin can help shift the timing of the circadian clock, and clinical guidelines support strategically timed melatonin for some people with DSWPD, but timing is crucial. Taking melatonin simply when you get into bed isn't necessarily the best way to shift a delayed clock, and more isn't necessarily better.

In the UK, melatonin is a prescription-only medicine. Although it can be bought from overseas websites, the NHS advises against ordering melatonin online. If you think melatonin might be appropriate for DSWPD, speak to your GP rather than trying to treat yourself with melatonin bought online. This is particularly important for children and teenagers.

When should you seek help for a delayed sleep schedule?

Simply going to bed earlier isn't always the answer. If your brain isn't biologically ready for sleep, an earlier bedtime may simply mean spending longer lying awake. Speak to your GP if your sleep timing is persistently delayed and is causing chronic sleep deprivation, making it extremely difficult to wake for school or work, affecting your mood or concentration, causing repeated lateness or absence, or proving very difficult to change.

Keeping a sleep diary for one to two weeks, including both working or school days and free days, can provide useful information to take with you.

It's also important to remember that other problems — including insomnia, insufficient sleep, medication effects, depression and other sleep disorders — can cause difficulty falling asleep or waking in the morning.

What does the latest research tell us about delayed sleep?

Perhaps the most useful question isn't:

“How do I make myself go to bed earlier?”

It's:

“What is keeping my sleep late?”

Is your biological clock genuinely delayed? Are evening habits pushing your sleep later? Are anxiety or arousal playing a role? Are you simply a healthy night owl trying to fit into a schedule that doesn't suit your biology? Or is it a combination?

The latest research on DSWPD suggests that understanding those differences could eventually help us personalise treatment much more effectively. The aim isn't to force everyone into the same bedtime. It's to understand why your sleep occurs when it does — and, if that timing is causing problems, find the right levers to change it.

References and further reading

1. Micic G, Reynolds AC, Phillips AJK, et al. Understanding delayed sleep-wake phase disorder (DSWPD): mechanisms, comorbidities, and evolving approaches to diagnosis and treatment. Sleep Medicine Reviews. 2026. Read the review.

2. Narala B, Ahsan M, Ednick M, Kier C. Delayed sleep wake phase disorder in adolescents: an updated review. Current Opinion in Pediatrics. 2024;36(1):124–132. Read the review.

3. Saxvig IW, Pallesen S, Wilhelmsen-Langeland A, et al. Delayed sleep phase syndrome in adolescents: prevalence and correlates in a large population-based study. BMC Public Health. 2013;13:1163. Read the study.

4. Auger RR, Burgess HJ, Emens JS, et al. Clinical practice guideline for the treatment of intrinsic circadian rhythm sleep-wake disorders. Journal of Clinical Sleep Medicine. 2015;11(10):1199–1236. Read the AASM guideline.

5. NHS. About melatonin. Read NHS guidance.