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Circadian Disorders
Circadian disorders are disorders of timing of brain and body activities associated with waking and sleeping. Changes in body temperature, the release of various hormones, and variations in brain chemistry can cause either alertness or sleepiness. A specific “clock” area in the hypothalamus area of the brain normally regulates these changes to promote alertness during the daylight hours and stimulate sleepiness a few hours after sundown. This wake/sleep promotion cycle typically works in conjunction with simple brain fatigue to cause us to sleep well at night and be most alert from morning to early evening. However, problems can occur that cause the circadian clock to promote alertness or sleepiness at the wrong times or not at all.
When people work night shifts, their circadian clocks may work against them, promoting sleepiness during the night shift, then promoting alertness that makes it hard to sleep during the day despite fatigue.
Another common circadian disorder is delayed sleep phase syndrome (DSPS), which is characterized by not feeling sleepy until very late at night and then wanting to sleep late into the daylight hours. DSPS may occur when exposure to daytime sunlight is reduced. Seasonal Affective Disorder is a form of DSPS occurring in the winter season. |
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