Overview of Delayed Sleep Phase Syndrome

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We often use the term "night owl" to describe someone who stays up late into the evening (and early morning) hours. But what explains the natural desire to stay up late and sleep in, especially in teenagers?

Discover the causes, symptoms, diagnosis, and testing, and treatments for delayed sleep phase syndrome. Consider the consequences, which include insomnia and sleep deprivation, and what can be done to keep the condition in check.


Anyone who stays up later than most people may be viewed as a potential night owl. However, those with delayed sleep phase syndrome may be birds of a different feather.

If the natural tendency to fall asleep is delayed by at least several hours compared to the average person (with a sleep onset closer to 1 a.m. to 3 a.m.), you may fit the description of someone with delayed sleep phase syndrome. In some cases, the sleep delay may be even more extreme, with a person going to sleep closer to sunrise.

The desire to wake up is similarly delayed by at least several hours in someone with delayed sleep phase syndrome. With a sleep onset closer to sunrise, the affected person may not wake up until early afternoon or later.

How Common Is Delayed Sleep Phase Syndrome?

It is estimated that up to 10% of the population could be characterized as having delayed sleep phase syndrome. It may be more common among teenagers, who are susceptible to a slight delay in their sleep timing, but it can persist through adulthood. There are many retired people who also experience the condition.


People with delayed sleep phase syndrome will generally experience two symptoms: insomnia and sleepiness. Why would these seemingly contradictory symptoms occur in the same person? It relates back to timing.


Most night owls will experience significant insomnia if they attempt to go to bed earlier than their natural desire for sleep onset. Crawling into bed at 10 p.m. may result in hours of lying awake, tossing and turning. This can provoke anxiety, frustration, and anger—feelings that make insomnia worse.

When left to stay up late on weekends or during vacation breaks, it suddenly becomes much easier to fall asleep. When sleep occurs, aside from being delayed, it can be normal and uninterrupted.

Morning Sleepiness

In the early morning hours, it can be difficult to wake a night owl. (Many parents have experienced futile attempts to drag their teenagers out of bed.) This morning sleepiness can be profound. Depending on the hour, it is akin to waking someone with normal sleep timing in the middle of the night.

It is extremely difficult to wake and function for those with delayed sleep phase syndrome. For night owls, their sleepiness decreases by mid-day. When the late evening rolls around, a night owl feels very awake, repeating the cycle again.

Social Pressure and Sleep Deprivation

Unfortunately, night owls are not typically allowed to sleep and wake when their bodies tell them to. If they could always go to bed at 2 a.m. and wake at 10 a.m., there would be no sleep problem. They would fall asleep easily, without insomnia, and wake easily without conflict. Unfortunately, pressure from the rest of society—parents, spouses, bosses, school systems—may be quite disruptive.

Without accommodation, chronic tardiness and absenteeism can lead to educational and professional dysfunction.

If someone does not naturally fall asleep until 2 a.m. but has to wake at 6 a.m. to be to work on time, sleep deprivation inevitably results.

Unfortunately, four hours of sleep is not enough to meet even basic sleep needs. This can have profound effects on health and well-being. Consider some of the symptoms associated with sleep deprivation:

  • Sleepiness
  • Fatigue
  • Difficulty concentrating
  • Memory problems
  • Mood changes (depression, anxiety, or irritability)
  • Errors or accidents
  • Physical pain
  • Hallucinations
  • Paranoia

There is some evidence that extreme sleep deprivation can be fatal. This is likely due to the chronic effects it produces.

ways to improve your sleep
Illustration by Brianna Gilmartin, Verywell


There seems to be a genetic predisposition towards developing delayed sleep phase syndrome. Some of this science is understood. For example, a mutation in the CRY1 gene alters the human circadian clock, delaying sleep by two to two-and-a-half hours compared to non-carriers. As researchers discover more about the condition, they will identify more of these so-called "clock genes" that play a role in the syndrome. Current research shows a hereditary component in 40% to 50% of "clock types" (whether you are a morning person or a night owl).

Beyond genetic programming, there are environmental factors that may unmask the condition. Most importantly, light has powerful effects on the timing of the circadian system. It may provoke the delay in sleep timing. However, it may also be used to correct the condition.

The Circadian System and Sleep

Sleep is dependent on two processes: sleep drive and the circadian alerting system. If isolated in a constant environment, like a cave, the genetically determined circadian timing will become evident. It is controlled by the suprachiasmatic nucleus, a region of cells in the hypothalamus of the brain, and highly influenced by light exposure. Every cell and organ in the body follows a circadian pattern.

For most people, this internal clock is programmed to run a little long, perhaps resetting every 24.5 hours. In the cave, without exposure to light variance, an isolated person would naturally fall asleep and wake 30 minutes later, with this timing shifting later each day. In a week, the timing of sleep would move three and a half hours.

In a month, it would shift 14 hours, so that the person would want to sleep during the natural day and be awake in the natural night. This natural drift in the circadian timing is reset with morning sunlight.

Exposure to natural light in the early morning hours is a signal to the brain for wakefulness. It makes it easier to wake. It also slightly shifts the timing of sleep earlier, making it easier to fall asleep. This helps to align the desire for sleep to the natural period of darkness overnight. Without it, significant problems can develop with sleep and health.


With proper education, it becomes fairly easy to recognize the symptoms of delayed sleep phase syndrome. It may be a lifelong affliction, starting in adolescence and persisting for decades.

Fortunately, testing is not required to reach a diagnosis. A careful history by a board-certified sleep physician can typically identify the condition.

In some cases, sleep logs kept over several weeks may aid the recognition. Rarely is testing with actigraphy (small monitors) needed.

In research settings, the measurement of melatonin levels can help to identify the circadian timing. In particular, the dim light melatonin onset (DLMO) measured via blood or saliva can establish the pattern. Unfortunately, repeated sampling requires a carefully controlled laboratory environment. This is virtually never done in clinical practice. Currently, researchers are working on blood tests to allow healthcare providers to determine internal circadian time.


If a condition is genetically determined and potentially lifelong, it may seem like a life sentence. Fortunately, for delayed sleep phase syndrome, this is not the case. There are effective ways to keep the timing of sleep in a normal phase. It may require a little extra effort, but consider the following potentially helpful interventions.


There is good evidence that night owls can maintain a socially acceptable sleep timing. This requires consistency, especially in regard to the wake time. Get up at the same time every day, including weekends. Do not sleep in.

Go to bed feeling sleepy, even if this initially requires a delay in the preferred bedtime. This will make it easier to fall asleep faster, relieve the pressure to sleep, and reinforce the sleep quality.

Morning Sunlight

It is especially important to reset the timing of sleep with morning sunlight. This is most effective immediately upon awakening. Try to go outside for 15 to 30 minutes upon awakening. Wake with an alarm, throw on clothes, and immediately get outside. Take a walk. Read the newspaper in the garden. Check social media while facing the sunrise.

The light should hit the eyes, but don’t stare directly into the sun. Even on a cloudy or rainy day, try to stick to the routine. In winter months, a light box may be necessary for phototherapy. The effects may take up to one month to become evident.

Avoid Light at Night

Artificial screen light should be minimized at night, especially in the hours preceding bedtime. It may shift the timing of sleep to occur later, causing insomnia and morning sleepiness. Devices may be switched to night mode, cutting out the blue light that can shift sleep timing.

Blue blocker sunglasses (with an amber tint) or screen covers may be employed. Or, simply shut down the electronics in the two hours before bedtime. The buffer zone before the goal bedtime should be spent relaxing.


Melatonin is a hormone produced overnight by the pineal gland in the brain. It can be an external signal to the circadian system, most effective among the blind. If taken up to six hours before the desired bedtime, it may help night owls to fall asleep earlier. The effects may be somewhat weak, however, and certainly overpowered by the effects of light.

Though melatonin is an over-the-counter product, be sure to speak with your heatlhcare provider to be safe before implementing any supplements in your routine.

Cognitive Behavioral Therapy for Insomnia

CBTI is an effective treatment that helps to improve the patterns of sleep and a person's relationship to it. Sleep consolidation, stimulus control, mindfulness, and relaxation techniques may be integrated into a program. It may be guided with help from a psychologist, class, online course, or book.


Rarely, it may be necessary to adjust the timing of sleep incrementally in a structured environment with chronotherapy. It is difficult to carry out at home and may require hospitalization. Over successive days, the sleep period may be delayed by one to two hours until the desired timing of sleep is achieved. Poorly timed light may complicate the efforts, and strict adherence to the final schedule must be observed.

Prescription Medications

Sleeping pills and stimulant medication to enhance alertness have a limited role in this condition. Generally, they will be weakly effective. As a result, they may be overused and even abused.

The risk of overdose in night owls, especially when these medications are used in combination with alcohol, is high. Instead of masking symptoms with a drug, the underlying timing of the circadian rhythm should be corrected.

Social Awareness

Education may help parents to appreciate what their teenager is experiencing, in order to realize that laziness or defiance isn't the issue. High schools should accommodate this natural timing among their students by shifting the school day—later school start times enhance academic performance, reduce tardiness and truancy, and even diminish car accidents among teens. Although this may not be an immediate option, it may be worth bringing it up at parent-teacher conferences or a school board meeting.

A Word From Verywell

Sleep deprivation can have serious impacts on health and well-being. If you are struggling with delayed sleep phase syndrome, consider seeking the guidance of a board-certified sleep physician. Start with some simple advice: go to bed feeling sleepy (even if later), keep a consistent wake time, and get sunlight upon awakening. If more help is needed, seek it out from a healthcare professional.

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Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Brandon Peters, MD
Brandon Peters, MD, is a board-certified neurologist and sleep medicine specialist.