What characterizes narcolepsy?

Narcolepsy is a neurological disorder that affects the control of sleep and wakefulness, and its primary characteristics include excessive daytime sleepiness and sudden episodes of REM sleep.

Excessive daytime sleepiness refers to a chronic condition where individuals feel an overwhelming desire to sleep during the day, often leading to unanticipated lapses into sleep during activities. This symptom can significantly impair daily functioning, making it difficult for affected individuals to maintain alertness.

The presence of sudden episodes of REM sleep is particularly distinguishing in narcolepsy. These episodes, known as sleep attacks, can occur at any moment and lead to a brief but sudden transition into REM sleep, during which dreaming occurs. This feature differentiates narcolepsy from other sleep disorders, where REM sleep typically occurs after a longer period of sleep rather than suddenly.

Given that both of these characteristics are fundamental to the diagnosis of narcolepsy, the correct answer encompasses both excessive daytime sleepiness and episodes of REM sleep, making the combination the best representation of the disorder's defining traits.