What is the primary clinical symptom of narcolepsy?

The primary clinical symptom of narcolepsy is characterized by uncontrollable urges to sleep. Individuals with narcolepsy experience excessive daytime sleepiness that often manifests as sudden sleep attacks, where they may fall asleep at inappropriate times, such as while eating, talking, or driving. This overwhelming need to sleep can be accompanied by a range of other symptoms, including cataplexy (sudden loss of muscle tone), sleep paralysis, and vivid hallucinations upon falling asleep or waking.

This symptom is distinct from chronic fatigue syndrome, which encompasses a broader range of fatigue-related issues and is not solely defined by sleep patterns. Loud snoring is typically associated with sleep apnea rather than narcolepsy, and while restfulness after sleep can be a common feeling for many, individuals with narcolepsy often do not feel refreshed after sleeping due to the fragmented sleep patterns typical of the condition. Thus, the urge to sleep plays a central and defining role in the diagnosis and understanding of narcolepsy.