Which sleep disorder is often marked by episodes of extreme daytime sleepiness and sudden sleep attacks?

Narcolepsy is characterized by episodes of excessive daytime sleepiness and sudden sleep attacks, which can occur at any time during the day. This disorder results from a dysfunction in the brain's ability to regulate sleep-wake cycles, leading to uncontrollable bouts of sleep that can last from a few seconds to several minutes. Individuals with narcolepsy may suddenly fall asleep while engaged in activities such as working or talking.

In contrast, insomnia primarily involves difficulty in falling or staying asleep, resulting in insufficient sleep but does not typically cause sudden sleep attacks. Sleep apnea is a condition in which breathing repeatedly stops and starts during sleep, often leading to fragmented sleep but not necessarily daytime sleepiness in the same way as narcolepsy. Restless legs syndrome involves uncomfortable sensations in the legs and an uncontrollable urge to move them, which can hinder sleep but is distinct from the sudden sleep episodes seen in narcolepsy.