Circadian Rhythm Disorders:  (sur cay dee yan) [circa = about, plus dies = day]  A group of sleep disorders affecting the timing of the sleep-wake cycle, among other biological rhythms. Both sleep and wakefulness occur at the wrong time, although the amount of sleep is usually adequate--if enough sleep time is allowed!  Normal human circadian rhythms  promote sleep at night, for about eight hours.


Click on the links below for more information about specific sleep-breathing disorders:

Delayed Sleep Phase Syndrome (DSPS):  the chronic inability to fall asleep (and therefore awaken after sleeping) until much later than desired. The timing of sleep is delayed for up to several hours. ...more

Advanced Sleep Phase Syndrome (ASPS):  the chronic need to fall asleep (and therefore awaken after sleeping) much earlier than desired. The timing of sleep is advanced for up to several hours. ...more

Shift Work Sleep Disorder: a work schedule that occurs during the normal sleep time and which results in an inability to adequately rest at another time. ...more

Jetlag:  the inability to attain a successful pattern of sleep and wakefulness following travel to a different time zone. ...more

Additional Circadian Rhythm Disorders:  any of several other Circadian Rhythm Disorders ...more