Narcolepsy

People with this condition experience unavoidable daytime sleepiness or sudden "attacks" of sleep during the daytime, in spite of adequate sleep during the night. Another disease that frequently affects people with narcolepsy is cataplexy. It causes sudden paralysis triggered by anger, joy or other emotional feelings which result in collapse.

Both conditions can make for embarrassing episodes in social situations. In addition, hypnogogic hallucinations (terrifying nightmares) might be experienced when a person is on the border between wakefulness and sleep, and complete body paralysis can occur. An overnight sleep study is essential to diagnose individuals with suspected narcolepsy. The analysis rules out other causes of daytime sleepiness and makes definitive treatment possible.