What would life be like if your sleep and wake times drifted later every day? How hard would it be if you began falling asleep in the morning, then in the afternoon, then in the evening as weeks went by?Just ask George Dawes Green, best-selling author of The Juror. USA Today describes how he sleeps around the clock because of this rare sleep disorder.
It is a circadian rhythm sleep disorder that is known by many names. It is called “free-running type” or “nonentrained type.” Sometimes it is called “non-24-hour sleep-wake syndrome” or “hypernychthemeral syndrome.”
The disorder is closely related to light and darkness.
Normally people have a circadian rhythm that is longer than 24 hours. But during the day and at night regular timing cues reset the body clock to a 24-hour schedule.
One of these timing cues is light. The light-dark cycle has the strongest influence on the timing of the brain’s clock. Without light, it is likely that your sleep time would drift later and later each day.
This is why people who are totally blind are most likely to have free-running type. It is rare for the disorder to occur in a person like Green who has normal eyesight.
Green told USA Today that he gets eight hours of sleep per day. But his sleep-wake schedule drifts about 20 minutes later each day.
People with this disorder often become isolated. Their varying sleep schedules can make it hard to maintain relationships.
It also can be difficult to succeed in school and keep a job. Green dropped out of school because he couldn’t stay awake in class.
As an adult he tried shift work, getting a job as a night guard. Then he started his own business.
Bright light therapy and melatonin can help treat free-running type. But Green chose instead to live with the disorder and follow his own sleep schedule.
Image by Russ Morris
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What is it?
Free-running (nonentrained) type is one of several circadian rhythm disorders. People with these disorders have sleep times that seem to be out of alignment. Their sleep patterns do not follow the “normal” sleep times at night.
The sleep time of people who have free-running (nonentrained) type shifts a little later every day. Sleep time and wake up time continue to move later and later every day. Sleep times go in and out of alignment with other people as weeks go by.
Normal people have a circadian rhythm that is longer than 24 hours. Every day, morning light and other behaviors reset the sleep-wake clock to a 24 hour schedule. Without light and this clock resetting, people’s sleep time will drift later and later. This is why many people who have free-running (nonentrained) type are blind. Light is the major influence on resetting the brain’s clock.
As your sleep pattern drifts a little later every day, free-running (nonentrained) type can be confused with other circadian rhythm disorders. As sleep time drifts later, you do not fall asleep until morning. It may seem like you have delayed sleep phase disorder. After days of later and later bedtime, you are sleeping during the day. After more days, you begin to sleep in the early afternoon and evening. This makes it look like you have advanced sleep phase disorder. After more days, you are back to sleeping during normal night hours. Then the drifting sleep time continues around the clock again. The sleep time is not broken up into pieces as with irregular sleep-wake type. The sleep time is only broken if there are outside disturbances. Your main sleep time does not occur at the same time every day. It continues to get later and later every day.
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