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Advanced Sleep Phase Syndrome

© Stephen Weistling

Our last article addressed Delayed Sleep Phase Syndrome (DSPS), which is characterized by the habitual need to go to sleep later than usual with a corresponding late awakening time. This causes shiftworkers much difficulty with early work starting times as well as when they need to retard their sleep habits during schedule changes. For our purposes, we refer to these people as “owls.”

Likewise, Advanced Sleep Phase Syndrome (ASPS) causes difficulty with persons who must stay up later than usual. ASPS is usually found in people who would call themselves “morning people” or “larks.” Larks generally find it easy to go to sleep early, and love to get up early. Larks are full of energy in the morning, love to talk, (and generally make life miserable for those who need time in the morning to “warm up.”)

There is a fundamental difference between the way larks and owls adjust to changing schedules. Whereas the owl (who stays up late) simply sleeps longer in response to a delayed bedtime, the lark will still get up at the same time in the morning regardless of the time they went to bed. This makes it extremely difficult for the lark (or person afflicted with ASPS) to adjust to changing schedules. After a few days of going to sleep later than usual, they accumulate sleep deprivation.

Scientists have found that exposing the subject to artificial light strong enough to resemble daylight can alter circadian rhythms. The reason that light therapy works as well as it does is that light affects the pineal gland. The pineal gland secretes melatonin which helps us sleep. When light is taken away, the secretion of melatonin increases and we begin to get drowsy. It is thought that in people who have ASPS, the connection between light, the pineal gland, and melatonin secretion is so strong that almost immediately as the sun goes down, melatonin production starts up and the poor ASPS sufferer immediately begins to think that it’s bedtime. This may have worked fine for farmers of the 19th century, but in today’s society (and especially the 24-hour society) it is a real problem.

ASPS may be corrected through exposure to bright light for two hours during the evening, which may shift the body’s circadian timing mechanism and delay the onset of sleep until a typical bedtime. Some may ask why typical house lighting in the evening won’t keep them awake until bedtime. That is because normal house lighting is well below the level of daylight. In order for light therapy to be effective, the intensity must be at least 5 times the level of normal house lighting. That means you need an illumination system that is in the neighborhood of 2500 lux.