Glossary

Apnea: Occurs when patients stop breathing during their normal sleep.  The brain rouses the sleeper to resume breathing, interrupting the sleep cycle.

Advanced Sleep Phase Syndrome:  When the major rest period begins earlier than desired. 

Circadian Rhythm:  The body’s internal resting/wakefulness schedule over the course of a day.

Delayed Sleep Phase Syndrome:  Occurs when people fall asleep more than two hours later then their desired bedtimes.

Narcolepsy:  A neurological disorder caused by the brain’s inability to regulate sleep-wake cycles.  People with narcolepsy experience fleeting urges to sleep throughout the day and can fall asleep for a few seconds, minutes, or hours.

Kleine-Levin Syndrome: A rare neurological disorder characterized by periods of excessive amounts of sleep and altered behavior.  At the onset of an episode the patient becomes progressively drowsy and sleeps for most of the day and night (hypersomnolence), waking only to eat or go to the bathroom. Most patients report that everything seems out of focus, and that they are hypersensitive to noise and light.