What is narcolepsy primarily characterized by?

Narcolepsy is primarily characterized by excessive daytime sleepiness, which is a hallmark symptom of the disorder. Individuals with narcolepsy often experience overwhelming drowsiness during the day, leading to sudden sleep attacks that can occur at any time, even during activities such as talking, eating, or driving. This excessive sleepiness is not due to poor sleep at night but is related to the neurological mechanisms that regulate sleep-wake cycles.

In addition to excessive daytime sleepiness, narcolepsy can involve other symptoms such as cataplexy (sudden muscle weakness), sleep paralysis, and hallucinations, but the primary defining feature remains the pronounced and uncontrollable need to sleep during daytime hours. This differentiates narcolepsy from insomnia and other sleep disorders that more commonly involve difficulties maintaining nighttime sleep or waking up refreshed.