Stage 4 Delta waves become even slower and more predominant in this deepest stage of sleep. Heart and breathing rates drop to levels 20 to 30 per cent below those in the waking state. Rem Beta and theta waves take over, with characteristic sawtooth patterns mixed in. Heart and breathing rates increase and become irregular, eyes dart in all directions. Body is immobile except for intermittent face, leg and finger twitches.
Dreams are vivid and emotionally charged.
Persons with narcolepsy, however, have a different pattern, passing into REM sleep nocturnal disturbances and considerably less restful sleep. They not only may report feeling as though they have not slept at all, but the nocturnal disruptions may exacerbate their symptoms of sleepiness. The presence, development, and severity of symptoms varies widely among individuals and may change over time. Not all persons with narcolepsy have all symptoms, but the existence of the tetrad of EDS, cataplexy, sleep paralysis, and hypnagogic hallucinations is diagnostic of narcolepsy and an indication of the eventual severity of the disease. Narcolepsy has been studied extensively, and the precise etologic factors that cause the disorder are unknown.