What Is Delayed Sleep-Wake Phase Disorder: Diagnosis and Treatment

Night Owls May Respond to Morning Light, Evening Melatonin

A teenage boy sleeps late due to delayed sleep-wake phase disorder
A teenage boy sleeps late due to delayed sleep-wake phase disorder. Getty Images

If you have trouble falling asleep and find it difficult to awaken in the morning, you may be interested in learning about a condition called delayed sleep-wake phase disorder. This surprisingly common cause of insomnia and morning sleepiness may explain your symptoms. What does it mean to have a delayed sleep phase? Learn about this circadian rhythm disorder common in night owls, why it occurs, how it is diagnosed, and treatment options including melatonin and light therapy.

What Is Delayed Sleep-Wake Phase Disorder?

In delayed sleep-wake phase disorder, the natural period of sleep is delayed when compared to the typical sleep timing of most people. As a result, someone with this condition will have trouble falling asleep at a common bedtime and will struggle to wake in the morning at a usual wake time. It commonly occurs among people who describe themselves as being night owls. The delay is typically two or more hours later than usual sleep times. For example, someone with delayed sleep phase may go to sleep at 2 AM and not easily awaken until 10 AM.

Individuals with this condition typically experience insomnia at bedtime (especially if they try to go to bed before they naturally feel sleepy). In addition, it can be very difficult to wake with extreme excessive sleepiness, or sleep inertia, upon awakening. When a strict conventional schedule is enforced, the combination of insomnia and forced awakenings may result in extreme sleep deprivation.

  • Example: Chris is a 16-year-old who likes to stay up until 2 a.m. and prefers to sleep in until 10 a.m. on the weekends. During the week, he struggles to get up and has multiple citations for tardiness and often skips his first classes. When he does go to these early classes, he feels extremely tired and performs poorly.

    In order to be diagnosed, symptoms must be persistent for at least 3 months. When sleep timing is more flexible, such as on vacation or over the summer in younger people, the insomnia and sleepiness improve. Though delayed, the sleep itself is otherwise normal and refreshing. There can be significant social and occupational dysfunction, including excessive absenteeism and tardiness.

    Other causes of insomnia and excessive daytime sleepiness should be excluded, including depression, anxiety, and sleep apnea. People with delayed sleep-wake phase disorder are at high risk for substance abuse as they struggle to induce sleep.

    Causes and Diagnosis of Delayed Sleep Phase

    Delayed sleep-wake phase disorder may first become evident in teenagers, but it may persist throughout life. It is estimated to affect 10 percent of people. 

    There may be a genetic tendency, as the condition often runs in families with 40% reporting a family history, and the hPer3 and Clock genes are associated with it. Exposure to light at night in susceptible individuals may provoke the pattern.

    The use of caffeine or stimulants at night may exacerbate the insomnia. It is common for other elements of insomnia to develop, including anxiety or frustration associated with the inability to fall asleep. 

    In general, delayed sleep-wake phase disorder may be diagnosed solely based on a careful history. When more information is needed, sleep logs and actigraphy measured over 1 to 2 weeks may be used. In some cases, a sleep study may be required to identify other potential causes of the symptoms, such as sleep apnea. 

    Treatment of Delayed Sleep-Wake Disorder

    Delayed sleep-wake disorder may be effectively treated with the use of phototherapy. Morning exposure to sunlight for 15-30 minutes upon awakening may be helpful in advancing the timing of sleep. If natural light is difficult to obtain, a light box may be used. In addition, other elements of cognitive behavioral therapy for insomnia (CBTI) may be employed. Moreover, a low dose of melatonin in the evening may be used, often taken several hours before the desired onset of sleep. The use of other sleeping pills is discouraged as they are often ineffective and have a high abuse potential.

    If the symptoms persist, it may be necessary to speak with a sleep specialist about the available options to optimize treatment.


    American Academy of Sleep Medicine. International classification of sleep disorders, 3rd ed. Darien, IL: American Academy of Sleep Medicine, 2014.

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