Delayed Sleep Phase Disorder: The Night Owl’s Dilemma

By Sheryl Grassie

Mar 19th, 2021

Expert Insights from Dr. Brooke Dulka, a medical writer and neuroscientist who received her Ph.D. in biological psychology from the University of Tennessee, and she is currently a postdoctoral researcher at the University of Wisconsin-Milwaukee where she studies the neurobiology of memory.

If you can’t fall asleep at a reasonable hour, and late night bedtimes are causing work/life challenges, you may have a problem with your circadian rhythm called delayed sleep phase disorder.

What is Delayed Sleep Phase Disorder?

Being a night owl may seem like a preference for many people. They would just rather to stay up late and sleep late in the morning. We all have friends or family that claim, “I do my best thinking late at night,” or “I get more done in the evening.” For the most part, we accept this as a naturally occurring rhythm; some people are just late night people, end of story.

However, staying up late and being awake and alert during evening hours, isn’t considered ideal. Some night owls don’t have a choice; they literally can’t fall asleep at a normal time. Having a very late bedtime can be a sign of a condition called delayed sleep phase disorder (DSPD), or more commonly, delayed sleep phase syndrome (DSPS).

“If you typically feel most alert in the evening and struggle with falling asleep at a certain time, you may be suffering from delayed sleep phase disorder,” says Dr. Dulka. “It becomes more of a problem when it starts interfering with work, school, or your mental health.”

Staying up late on a regular basis causes a disruption of our internal body clock, our circadian rhythm, and once disregulated, it may be extremely difficult to fall asleep earlier. Some people just adapt by going to bed much later than the norm, but if sleep is delayed by two or more hours, it is actually considered a sleep disorder. Our inborn biological clocks want us to sleep with the dark and wake with the sun. Some people’s rhythms become disturbed and they can’t fall asleep until the wee hours.

Many night owls, since they are awake and alert during the evening hours, don’t get enough overall sleep and experience a disrupted weekly schedule. They go to bed late, but if they need to be up for work, or school, or other commitments, they force themselves to get up at a reasonable hour. They are often reduced to sleeping short, but generally uninterrupted, hours during the week, and making up for it with longer periods of sleep on the weekend.

This kind of sleep pattern, which is contrary to the natural rhythms of light and dark, falls under the broader category of circadian rhythm sleep disorder. The night owl syndrome or more clinically the delayed sleep phase disorder is considered fairly common; especially in adolescents where between 7-16% of the population is experiencing it at any given time.

Symptoms of Delayed Phase Sleep Disorder

Delayed sleep phase disorder is hallmarked by feeling most alert in the evening and an inability to fall asleep at the desired time. Individuals with this disorder have an overall sleeping and waking schedule that is pushed back by at least two hours. They generally go to bed between 1-4 AM. and wake between 8-11 AM. The inability to fall asleep is considered a form of insomnia, but when coupled with an inability to wake up it is considered a sleep disorder. For people with delayed sleep phase disorder, the challenge with sleep is on both ends and the entire schedule is pushed back.

There are generally no other sleep problems associated with the disorder, so an individual might experience themselves as sleeping well, just much later than the norm. People with this night owl schedule can however, experience being very sleepy during the day, and there are a substantial number of individuals, about 50%, that have comorbid depression or behavior problems.

When is being a night owl a problem? When it interferes with work or school, or when it is evident it is causing depression or other behavioral health issues. It then ceases to be just a syndrome and is classified as a disorder.

Circadian Rhythm Sleep Disorders

Circadian rhythm sleep disorders, is a broader category that covers a number of clinical variations to the norm in regards to the sleep awake cycle. These deviations are all relative to light and dark cycles that occur in the course of a day, or a 24-hour cycle.

The term circadian is derived from the Latin, circa meaning about, and diem meaning day, meaning “about a day” or “in the course of a day.” Our circadian rhythm is essentially our internal clock for a day; how much we should sleep and when, how much we should be awake and when. Our bodies naturally synchronize with our external environment and the natural schedule of light and dark. Our circadian rhythm adjusts in the course of the year, sleeping more when there are more dark hours in the winter and less when it is lighter in the summer.

There are a several different ways in which circadian rhythm sleep disorders are classified:

  • International Classification of Diseases (ICD-10-CM, 2014) lists delayed sleep phase type, free-running type, advanced sleep phase type, irregular sleep-wake type, shift work type, jet lag type.
  • Diagnostic and Statistical Manual of Mental Disorders (DSM – 5) lists six types of circadian rhythm sleep disorders (CRD) that fall under the 307.45 heading. These include; delayed sleep phase type, advanced sleep phase type, irregular sleep-wake type, non-24-hour sleep-wake type, shift work type, and unspecified type.

The DSM-5 further outlines three categories.

  1. Episodic, where symptoms last between a month and three months
  2. Persistent, where the symptoms last more than three months
  3. Recurrent, which consists of two or more occurrences within a one year timeframe

There are a number of different criteria and classifications, but the literature generally supports recognition of the following conditions:

Advanced Sleep Phase Syndrome (or Disorder) (ASPS or ASPD)

ASPS or ASPD are characterized by the need to go to sleep very early. Individuals go to sleep and wake much earlier than the norm. They may fall asleep very early in the evening, well before the sun sets, and get up in the dark early morning hours before sunrise. This is a more common pattern for seniors who sleep less in general and often wake very early.

Delayed Sleep Phase Syndrome (or Disorder) (DSPS or DSPD)

DSPS or DSPD are characterized by going to sleep and waking much later than the norm. The classic night owl goes to bed in the wee hours and sleeps until noon, with their most awake and productive time being in the evening.

Irregular Sleep-Wake Disorder (ISWD)

ISWD is characterized by a pattern of sleeping and waking in smaller segments. They may nap twice during the day and sleep a shorter time overnight, or go to bed early and get up and work for hours in the middle of the night, then go back to sleep and also take an afternoon nap. A minimum of three separate sleep periods need to take place to meet the criteria for this disorder.

Shift Work Sleep Disorder (SWSD)

SWSD is characterized by an inability to adjust to altered sleep times imposed by external work circumstances. For example, if you work overnight shifts and then can’t fall asleep during the day when you have time to sleep.

Read more: What is shift work sleep disorder?

Reverse Sleep

Reverse sleep is when the body’s clock is reversed for internal or external reasons. The person sleeps during the day and is awake at night. You might hear a reference to babies, that he or she has their days and nights mixed up.

Jet Lag

Jet lag is usually a temporary condition where your sleep schedule is thrown off. It is caused by travel and changes in time zones. Some people can be greatly affected and take numerous days to re-regulate, while others can move through time zones with little or no effect on their circadian rhythm.

Non-24-Hour Sleep-Wake Disorder (Non-24)

Non-24 is a more complicated sleep schedule characterized by the person’s day being longer than a 24 hour period. Their internal “day” might be 30 hours and they might sleep and wake proportionate to that amount of hours. For example they might sleep 8 hours out of every 30 hours essentially changing the times of sleeping and waking relative to the 24 hour clock.

What Causes Delayed Sleep Phase Disorder?

“Causes for delayed sleep disorder include a combination of both genetic and environmental factors such as a family history of delayed sleep,” explains Dr. Dulka. “Other causes include poor sleep hygiene like being exposed to too much light in the evening.”

Research indicates around 40% of people with the disorder have a family history of delayed sleep, or a family member with the disorder, pointing towards a predisposition. Recent research has explored the role of human leucocyte antigen DR1 in this disorder along with genetic polymorphisms in the PER3 gene (related to circadian rhythms) in DSPD.

Poor sleep hygiene can also contribute to having delayed sleep phase conditions. The most significant sleep hygiene factor is light, and especially a lack of outdoor morning light or too much light in the evening, can affect melatonin production and contribute to delayed sleep.

Treatments for Delayed Sleep Phase Disorder

“Delayed sleep phase disorder can be tricky to treat, but the use of melatonin or practicing good sleep hygiene like eating less sugar or putting your phone down 2 hours before bed can be used to help combat DSPD,” says Dr. Dulka.

In general, delayed sleep phase disorder is difficult to treat. The following are the primary interventions used to reset the circadian rhythm of those challenged by the disorder.

Bright Light Therapy (BLT) is the number one recommendation for correcting delayed sleep phase disorder. A part of good sleep hygiene, it can be done naturally with more time outside in sunlight, especially in the mornings and less exposure to light indoors in the evenings. Light therapy boxes or trays can be purchased and used to simulate daylight. This is an easy way to resent circadian rhythm and re-regulate melatonin production to aid in a more natural sleep rhythm.

Chronotherapy is a behavioral approach where you train yourself slowly to sleep at an earlier time. Instead of trying to move up your bedtime, you actually push it back later, several hours a day until you go all the way around the clock to the desired bedtime. This can take up to a couple of weeks and is somewhat disruptive when you are going to bed and sleeping during the day. The delayed sleep phase disorder needs to be severe enough to motivate the patient to engage in this more rigorous treatment.

Cognitive Behavioral Therapy (CBT) is a therapeutic approach with an educational component. “CBT is a psychological therapy method that works by changing peoples’ attitudes and perceptions by focusing on recognizing how thoughts, for instance, relate to a way a person behaves,” says Dr. Dulka. CBT is often used in conjunction with bright light therapy to help regulate the circadian rhythm. A patient might be educated about the body’s internal clock, the importance of light, and good sleep hygiene. Next they might be taught relaxation techniques or asked to keep a sleep journal. If there is anxiety associated with trying to go to sleep, the CBT therapist might work to create a different stimulus response pattern for the patient; a pattern where the thought of bed, and sleep, triggers happy relaxing thoughts instead of anxiety. CBT can be individualized to meet the needs of a given patient.

Melatonin is the body’s natural drowsiness hormone. It helps put you to sleep and keep you sleeping by synchronizing circadian rhythms. If there is not enough naturally occurring melatonin in your system, you can supplement it. There is organic melatonin and synthetic melatonin, which can be taken orally 30 minutes before bedtime to help induce sleep. Tart cherry juice twice daily provides supplemental melatonin and supports the body’s natural production of melatonin.

Good Sleep Hygiene:

  • Refrain from caffeine later in the day
  • Avoid napping
  • Don’t eat after dinner
  • Avoid alcohol
  • Eat less sugar
  • No screen time for two hours before bed
  • Maintain a consistent sleep schedule, go to bed and get up at the same time every day
  • Get enough exercise
  • Have exposure to outdoor sunlight in the morning
  • Get fresh air daily
  • Do something relaxing before bed like taking a bath or reading
  • Reduce artificial light in the evening
  • Maintain a healthy weight
  • Sleep in a quiet, cool, dark room,  using light blocking curtains if needed


Night owls may have a dilemma. Are their late night hours a choice they can live with, or do they indicate some type of circadian rhythm sleep disorder? If a normal bedtime is routinely delayed by two or more hours, and the late night schedule interferes with work or other parts of life, it may be delayed sleep phase disorder. The best guess as to cause is a combination of genetics and lack of daylight. Although hard to treat, bright light therapy, resetting the circadian rhythm, and increased melatonin can all help.

Expert Bio

Expert Bio

Dr. Brooke Dulka is a medical writer and neuroscientist. She recieved her Ph.D. in biological psychology from the University of Tennessee, and she is currently a postdoctoral researcher at the University of Wisconsin-Milwaukee where she studies the neurobiology of memory.