American Board of Psychiatry and Neurology (ABPN) Practice Exam 2026 - Free ABPN Practice Questions and Study Guide

Narcolepsy is characterized by episodes of sudden sleep onset, which can occur unexpectedly during the day, and cataplexy, a condition where individuals experience a sudden loss of muscle tone, often triggered by strong emotions such as laughter or excitement. In narcolepsy, these episodes of sleep can be brief, lasting only a few seconds to several minutes, and may happen multiple times a day.

The presence of cataplexy distinguishes narcolepsy from other sleep disorders. This phenomenon is specific to narcolepsy and is not found in conditions like sleep apnea, insomnia disorder, or REM sleep behavior disorder. While sleep apnea involves interrupted breathing during sleep and can lead to excessive daytime sleepiness, it does not include sudden sleep attacks or cataplexy. Insomnia disorder primarily involves difficulty initiating or maintaining sleep without the sudden sleep episodes characteristic of narcolepsy. REM sleep behavior disorder involves acting out dreams during REM sleep, which also does not relate to sudden sleep onset or cataplexy.

Thus, the distinctive combination of sudden sleep attacks and cataplexy supports the diagnosis of narcolepsy, making it the correct choice.