Updated February 26, 1999

Please see our updated article about delayed sleep phase syndrome on the new Stanford Sleep and Dreams website.

What is Delayed Sleep Phase Syndrome (DSPS)?

It is a disorder in which the major sleep episode is delayed by 2 or more hours of the desired bedtime. This causes difficulty awakening at the desired time.

What are the symptoms?

Associated features:

The DSPS patients are usuall perplexed that they cannot find a way to fall asleep more quickly. Their efforts to advance the timing of sleep onset such as going to bed early, having a friend or family member get them us in the morning, trying relaxation techniques or using sleeping pills is not permanently successful.

They often describe sleeping pills in normal doses as having little or no effect in helping them fall asleep. Sometimes the pills only aggravate the daytime symptoms of difficulty awakening and sleepiness.

DSPS patients typically are "owls" or "night people" and say they feel and function best and are more alert during the late evening and night hours.

If a sleep-wake log is kept, it usually shows a pattern of bedtime later than 2 a.m., few or no awakenings once they fall asleep, shorter sleep periods during the work/school week and lengthy (9-12 hour) sleeps with late morning to mid-afternoon wake up times on the weekend.

Depression or other psychiatric problems are present in about half of the adult DSPS patients, which is about the same for people that suffer from other forms of insomnia.

At what age does DSPS begin to show up?

Many DSPS patients report that their difficulties began after a period of late night studying or partying, or after employment on the evening or night shift. Following these activities, they found it impossible to sleep on a normal schedule even when they resumed normal work or school hours. Adolescence appears to be the most common period of life for the onset of DSPS, but childhood cases have been reported. It is rare for it to begin after age 30.

Adolescents and DSPS

How can it be treated?

Read more about the treatment of delayed sleep phase syndrome from the new Stanford Sleep and Dreams website.


Bright Light Therapy

Bright light therapy takes total control of light and dark exposure across the whole day. The patient uses bright light exposure early in the morning and avoids light in the evening. This should produce a phase advance. Two hours (upon rising in the early morning) in front of a light box that emits 2500 lux will usually produce and increase in alertness in one week.


Chronotherapy is a behavioral technique in which bedtime is systematically delayed, which follows the natural tendency of human biology. Bedtime is delayed by 3 hour increments each day, establishing a 27-hour day. The procedure is maintained until the desired bedtime is reached, (say 11 p.m.) when the normal 24-hour day is then established.

The patients problem in having DSPS is that they have the inability to synchronize to a phase advance. The patient is told to maintain the new bedtime rigidly and told not to delay bedtime to study, party or travel westward.


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