Narcolepsy, also known as hypnolepsy, is a chronic neurological disorder caused by autoimmune destruction of hypocretin-producing neurons inhibiting the brain's ability to regulate sleep-wake cycles normally. People with narcolepsy experience frequent excessive daytime sleepiness, comparable to how non-narcoleptics feel after 24 to 48 hours of sleep deprivation, as well as disturbed nocturnal sleep which often is confused with insomnia.