Then in a little bit, boom, they'd jump up like nothing happened. Like a switch again. Symptoms in humans are very similar, if not always as dramatic. Most people with narcolepsy describe bouts of relentless or irrepressible sleepiness in the daytime, even if they have slept soundly the night before. With little warning, they can rapidly doze off and become limp - even in the midst of conversation, preparing a meal, or other tasks.
Episodes usually last a few minutes and can occur several times a day.
About 125,000 Americans suffer from the disorder. The Stanford dogs and Southwestern rats share two hallmarks of human narcolepsy that, combined with the feeding behavior link, suggest the disorder may open a window on deeply rooted systems in the brain. First, episodes can be triggered by excitement, fear, or some other strong and often sudden emotion. Second, the sleep into which narcoleptics slump is abnormal. In narcolepsy, however, the patient lapses directly from wakefulness to REM sleep, and back to wakefulness.