Narcolepsy /ˈnɑrkəˌlɛpsi/, also known as hypnolepsy, is a chronic neurological disorder involving the loss of the brain’s ability to regulate sleep-wake cycles normally. People with narcolepsy experience frequent excessive daytime sleepiness, comparable to how people who don’t have narcolepsy feel after 24 to 48 hours of sleep deprivation, as well as disturbed nocturnal sleep which often is confused with insomnia. Those with narcolepsy generally experience the REM stage of sleep within 5 minutes of falling asleep, while people who don’t have narcolepsy (unless they are significantly sleep deprived) do not experience REM until after a period of slow-wave sleep, which lasts for about the first hour or so of a sleep cycle. Another common symptom of narcolepsy is cataplexy, a sudden and transient episode of muscle weakness accompanied by full conscious awareness, typically (though not necessarily) triggered by emotions such as laughing, crying, terror, etc. affecting roughly 70% of people who have narcolepsy.