What is the condition called when a person suddenly falls asleep without any warning?

The condition in which a person suddenly falls asleep without any warning is known as narcolepsy. This neurological disorder is characterized by excessive daytime sleepiness and sudden sleep attacks, which can occur at inappropriate times, such as while talking, working, or driving. Individuals with narcolepsy may also experience phenomena such as cataplexy, which involves a sudden loss of muscle tone triggered by strong emotions, and hallucinations upon falling asleep or waking up.

In contrast, sleep apnea refers to a condition where breathing stops and starts repeatedly during sleep, leading to fragmented sleep and excessive daytime sleepiness. Insomnia involves difficulty falling asleep or staying asleep, while hypersomnia is characterized by excessive sleepiness during the day, but not necessarily sudden sleep attacks. Understanding these distinctions clarifies why narcolepsy is the correct answer for the sudden onset of sleep episodes.