Delayed Sleep Phase Syndrome and Advanced Sleep Phase Syndrome

What is delayed sleep phase syndrome (DSPS)?
Delayed sleep phase syndrome (DSPS) is a disorder of sleep timing. People with DSPS tend to fall asleep at very late times, and will subsequently sleep later in the day having difficulty waking up in time for normal work, school, or social needs.

What causes DSPS?
The exact cause of DSPS is not known, but the disorder is related to circadian rhythms, which regulate the internal biological clock and influence functions such as sleep-wake patterns. DSPS can occur in people who have experienced head trauma or serious illnesses. In these cases, the body's natural healing process might disrupt normal circadian rhythm and leave the biological clock unable to reset itself. Many teenagers tend to have delayed sleep phase but often grow out of it.

What are the symptoms of DSPS?
DSPS is characterized by the inability to fall asleep before early morning (for example, midnight to 3 a.m.) and difficulty waking in the morning. Usually, people who have DSPS can fall asleep when the body signals that it is time. Sleepiness does not usually occur before this delayed period. If a person tries to force the body into a particular phase, symptoms such as excessive daytime sleepiness, fatigue, and altered eating habits might develop.

How is DSPS treated?
DSPS treatments are meant to adjust a personís circadian rhythm and sleep pattern. The goal of treatment is to fit a personís sleep pattern into a schedule that can allow the person to meet the demands of a desired lifestyle. Treatment is meant to allow the person with DSPS to wake up at a given time feeling refreshed and functional. People receiving treatment gradually adjust to an earlier bedtime with sleep therapy. This therapy usually combines proper sleep hygiene practice and external stimulus therapy such as bright light therapy and chronotherapy. Chronotherapy is a behavioral technique in which bedtime is systematically adjusted. Bright-light therapy is designed to reset a personís circadian rhythm to the desired pattern. When combined, these therapies might produce significant results in people with DSPS. Patients can also be treated with one medicine that puts them to sleep earlier in the evening and another medicine that helps wake them up in the morning, but this form of treatment is usually used only in extreme cases.

What is advanced sleep phase syndrome (ASPS)?
Advanced sleep phase syndrome (ASPS) is a disorder in which a personís sleep time is early in relation to the time of day. This syndrome results in symptoms of evening sleepiness, an early sleep onset, and an awakening time that is earlier than desired.

What causes ASPS?
The disorder is related to circadian rhythms, which regulate the internal biological clock and influence functions such as sleep-wake patterns. People with this sleep disorder have not been studied extensively, but familial inheritance of this condition has been reported. This condition is more likely to appear in the elderly.

What are the symptoms of ASPS?
People with advanced sleep phase syndrome have:

In people who have ASPS, daytime school or work activities are not affected by sleepiness. However, evening activities are cut short by the need to retire early. Typical sleep onset times are between 6 and 8 p.m., and no later than 9 p.m., and wake times between 1 and 3 a.m., and no later than 5 a.m. These sleep-onset and wake times occur despite a personís best efforts to delay sleep to later hours.

How is ASPS treated?
Advanced sleep phase syndrome is treated with chronotherapy--a behavioral technique in which bedtime is systematically delayed--or with bright light therapy. Bright-light therapy is designed to reset a personís circadian rhythm to a later hour.

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This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition. For additional health information, please contact the Center for Consumer Health Information at the Cleveland Clinic (216) 444-3771 or toll-free (800) 223-2273 extension 43771. If you prefer, you may visit www.clevelandclinic.org/health/ or www.clevelandclinicflorida.org. This document was last reviewed on: 2/10/2005

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