The influence of orexin on sleep and wakefulness

An exciting recent development in sleep research was the discovery of the importance for vigilance state control and narcolepsy-cataplexy of neurons containing orexin (also known as hypocretin) neuropeptides. Narcolepsycataplexy is a chronic, debilitating sleep disorder that is characterized by excessive daytime sleepiness, manifested as attacks of daytime somnolence at inappropriate times. ^1-3 Narcoleptics also show symptoms that are considered indicative of abnormal REM (Rapid Eye Movement) sleep expression. These latter symptoms include cataplexy, hypnogogic hallucinations, sleep-onset REM periods, and sleep paralysis. In contrast to daytime sleepiness, the nighttime sleep of narcoleptics is fragmented and of poor quality, typically demonstrating lengthy periods of wakefulness after sleep onset