Delayed sleep phase

Learn more about this sleep condition that causes a delay in usual sleep patterns.

Update Date: 27.02.2026

Overview
Symptoms
Causes
Risk factors
Complications
Prevention
Diagnosis
Treatment
Coping and support
Preparing for an appointment

Overview

Delayed sleep phase is a condition that affects the body's internal clock, known as circadian rhythm. People with delayed sleep phase have sleep patterns that occur two or more hours later than usual patterns. They go to sleep later and wake later. This makes it hard to get up in time for work or school. Delayed sleep phase also is known as delayed sleep-wake phase disorder.

A treatment plan might include making changes to sleep habits, taking melatonin supplements and using light therapy.

Symptoms

Symptoms of delayed sleep phase include falling asleep and waking up later than usual. Sleep and wake times are delayed at least two hours and may be delayed up to 3 to 6 hours. For example, people with delayed sleep phase may regularly go to sleep at 3 a.m. and wake at 10 a.m.

Delays in sleep and wake times last at least three months and often for years. Symptoms may include:

  • Not being able to fall asleep at a typical bedtime, known as insomnia.
  • Trouble waking up in the morning in time to go to work or school.
  • Extreme daytime drowsiness.
  • Trouble staying alert during the day.

When to see a doctor

See a healthcare professional if you have persistent symptoms of delayed sleep phase. Or make an appointment for your child if you think your child has these symptoms and they don't go away.

Also make an appointment if you or your child regularly has trouble waking in the morning or has excessive daytime drowsiness.

Causes

Delayed sleep phase is caused by a person's internal clock being out of sync with the environment. Your internal clock lets you know when it's time to sleep and when it's time to wake. Known as circadian rhythm, your internal clock is on a 24-hour cycle. Cues in the environment influence the sleep-wake cycle. These cues include light, darkness, eating and physical activity.

The exact cause of delayed sleep phase isn't known. But circadian rhythms can be delayed in teenagers for biological reasons. Staying up late to do homework, watch TV or spend time online can make the sleep delay worse.

Risk factors

Delayed sleep phase can affect children and adults of any age. However, the condition is more common among teenagers and young adults.

Complications

Teenagers with delayed sleep phase can have complications, such as poor performance in school and behavior issues, including attention-deficit/hyperactivity disorder (ADHD). Delayed sleep phase also has been associated with autism spectrum disorder.

In teenagers and adults, it's common to have depression and anxiety along with this sleep condition.

Prevention

Some lifestyle changes can help prevent delayed sleep phase. Follow a regular, consistent bedtime schedule and limit bright light and screens before bed to help you sleep.

Diagnosis

To diagnose delayed sleep phase, also known as delayed sleep-wake phase disorder, a healthcare professional reviews your family and medical history. You also may have a physical exam.

Several tests can help diagnose delayed sleep phase or any related conditions, such as:

  • Actigraphy. This test tracks your sleep and wake times over multiple days. During the test, you wear a small device on your wrist that detects your motions. The device also may monitor light exposure.
  • Sleep diary. For a week or longer, you log your daily sleep and wake times to understand your sleep patterns.
  • Sleep study, also known as polysomnography. If it's suspected that you might have another sleep condition, you may need a sleep study. For this test, you may need to stay in a sleep center overnight. Polysomnography monitors your brain activity, heart rate, oxygen levels, eye movements and breathing function as you sleep.

Treatment

A healthcare professional works with you to create a treatment plan that can help adjust your sleep and wake times.

Your plan may include:

  • Lifestyle changes. Changes to your sleep routine can improve your sleep habits. This is known as sleep hygiene. To practice good sleep hygiene, go to bed and get up on a regular schedule, including on the weekends. It's best not to take naps during the day. Don't drink caffeine or alcohol near bedtime, and don't use tobacco products. Exercising during the day also helps improve sleep, but finish your workout at least two hours before bedtime. It's also helpful not to engage in stimulating activities near bedtime. Use your bedroom only for sleeping and sex.
  • Melatonin supplements. Melatonin is a hormone that plays a role in the sleep-wake cycle. Your healthcare professional may recommend taking a melatonin supplement in the early evening. This can help adjust your circadian rhythm to go to sleep earlier.
  • Light therapy. Light exposure using a light box in the morning may help adjust your circadian rhythm.
  • Chronotherapy. For some people, healthcare professionals prescribe a sleep schedule that delays bedtime by 1 to 2.5 hours every six days. This is done until the desired bedtime is reached. You need to maintain your sleep schedule once it is established.

Coping and support

Sleep conditions such as delayed sleep phase can affect how well you perform at work and school, and they may lead to depression and anxiety. These tips may help:

  • Ask your family for support. It may be easier to stick to a sleep routine if your family practices sleep hygiene along with you. Ask family members to support your earlier bedtime by lowering the lights, making the house quiet and turning off electronics two hours before bed.
  • Treat your mental health. Let your healthcare team know if you're experiencing symptoms of depression or anxiety. Getting treatment can help you cope as you work on adjusting your sleep-wake cycle.

Preparing for an appointment

See your healthcare professional if you have sleep symptoms that concern you. Your healthcare professional might refer you to a sleep specialist.

What you can do

Ask if there's anything you need to do in advance of your appointment, such as keep a sleep diary.

Make a list of:

  • Your symptoms, including any that may seem unrelated to the reason for which you scheduled the appointment. Include when your symptoms began.
  • Family history, including any relatives who have a sleep condition.
  • All medicines, vitamins and supplements that you take, including the doses.
  • Questions to ask your healthcare professional.

Consider asking a family member or friend to come along, if possible, to help you remember the information you're given.

For delayed sleep phase, questions to ask your healthcare professional may include:

  • What tests do I need? How do I prepare for the tests?
  • Is my condition likely short-term or long lasting?
  • What treatments are available? Which treatments are best for me?
  • I have other health conditions. How can I best manage these conditions together?
  • Should I see a specialist?
  • Are there brochures or printed material about my condition that I can take? What websites do you recommend?

Don't hesitate to ask other questions.

What to expect from your doctor

Your healthcare professional is likely to ask you several questions, such as:

  • When did your symptoms begin?
  • Have your symptoms been constant or on and off?
  • How bad are your symptoms?
  • What, if anything, seems to improve your symptoms?
  • What, if anything, seems to worsen your symptoms?
  • How is your sleep when you follow your preferred sleep schedule?

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