Which is NOT a symptom of Narcolepsy?

Insomnia is indeed not a symptom of narcolepsy. Narcolepsy primarily involves excessive daytime sleepiness (hypersomnolence), alongside other key features such as cataplexy, which is a sudden loss of muscle tone often triggered by strong emotions, and specific abnormalities on polysomnography (PSG) during sleep studies.

In narcolepsy, individuals typically experience profound drowsiness and may have difficulty staying awake during the day. They also may enter REM sleep more quickly than those without the disorder, which is reflected in characteristic PSG findings. Insomnia, characterized by difficulty falling or staying asleep at night, is usually seen in different sleep disorders rather than narcolepsy, where individuals generally have a tendency towards excessive sleep rather than an inability to sleep.