DSM-5 Disorders Practice Exam Prep: Practice Test & Study Guide

Narcolepsy is characterized by a short REM-sleep latency, which means that individuals with this condition transition quickly into REM sleep, often within 15 minutes of falling asleep. This rapid onset of REM sleep is one of the hallmark features of narcolepsy and is associated with excessive daytime sleepiness and sudden sleep attacks.

In contrast, conditions like insomnia disorder are characterized by difficulties in initiating or maintaining sleep, rather than the timing of REM sleep. Obstructive sleep apnea hypopnea primarily features repeated episodes of partial or complete blockage of the airway during sleep, leading to disrupted sleep patterns but not necessarily a short REM-sleep latency. Circadian rhythm sleep-wake disorders involve a misalignment between an individual's internal clock and their environment, which can impact sleep timing but does not inherently cause a rapid transition to REM sleep. The distinction of having a shortened REM-sleep latency is thus a significant indicator of narcolepsy.