American Board of Psychiatry and Neurology (ABPN) Practice Exam

Which sleep disorder is characterized by episodes that may occur during stage IV sleep and can involve injuries or violent behavior?

1. A. Night terrors

2. B. Narcolepsy

3. C. Somnambulism

4. D. Insomnia

The correct answer is: C. Somnambulism

The correct answer is somnambulism, commonly known as sleepwalking. This disorder typically occurs during non-REM sleep, particularly during slow-wave sleep or stage IV sleep, which is the deepest stage of sleep. Individuals experiencing somnambulism may engage in complex behaviors while still asleep, including walking around, performing routine tasks, or even exhibiting violent behavior. These episodes can sometimes lead to injuries for both the sleepwalker and others nearby, as they are unaware of their actions. Night terrors, although they can involve violent behavior, typically occur during stage III and IV (slow-wave) sleep, primarily in children, and the individual usually does not remember the episode afterward. Narcolepsy involves excessive daytime sleepiness and sudden sleep attacks but does not generally manifest as violent behavior during sleep episodes. Insomnia refers to difficulty falling asleep or staying asleep and does not connote any physical activity during sleep. Thus, when considering the characteristics of episodes occurring during stage IV sleep that may result in injuries or violent behavior, somnambulism stands out as the most accurate representation.