What characterizes narcolepsy?

Narcolepsy is primarily characterized by uncontrollable sleep attacks, which are sudden episodes of overwhelming daytime sleepiness that can occur at any time and can last from a few seconds to several minutes. These sleep attacks can interrupt daily activities and are a hallmark of the disorder.

Individuals with narcolepsy may also experience cataplexy, which is a sudden loss of muscle tone usually triggered by strong emotions, but the defining feature remains the unexpected and intense sleepiness. This condition results from the brain's inability to regulate sleep-wake cycles effectively.

The other options describe different sleep-related issues that do not specifically define narcolepsy. Excessive snoring is more associated with sleep apnea, frequent nightmares often relate to various sleep disorders or psychological factors, and insomnia from anxiety pertains to difficulties falling or staying asleep due to stress or worry, none of which are central characteristics of narcolepsy.