8. Narcolepsy
Potentially a very disruptive and potentially dangerous condition, narcolepsy is characterized by the sufferer’s tendency to fall asleep suddenly and without warning. Oftentimes, people with narcolepsy pass from a wakeful state to REM sleep in a matter of seconds. In some people, it can be triggered by intense emotional responses. Researchers are still not certain of the cause, but treatment using stimulant and anti-depressant medications are sometimes used.