Perhaps one of the best known, and yet still weird, sleep disorders is narcolepsy, which has a tendency to put people to sleep unexpectedly while they are engaged in normal, everyday activities, such as driving, jogging or washing dishes.
Narcolepsy is a neurological sleep disorder that is commonly associated with falling asleep at random times. Narcoleptics tend to fall directly into REM sleep, when most dreaming occurs, and less commonly enter deeper and more restful stages of non-REM sleep. As a result, they are unable to stay awake for extended periods of time, and upon falling back asleep, they still are unable to experience sleep's more restorative stages, causing a vicious cycle of extreme sleepiness and inability to stay awake after having slept. Another symptom can include cataplexy, the sudden collapse of an individual into REM sleep upon experiencing strong emotions. Sleep paralysis and hypnogogic hallucinations (hallucinations which accompany sleep paralysis) are also known to be symptoms. The cause of narcolepsy has not been determined. It is widely believed to be an autoimmune disorder, but it may also be genetic. Treatments include stimulants, anti-depressants, or hypnotic medications such as Xyrem. (Link)