Sleep walking is seen in which stage of sleep ?
**Core Concept**
Sleep walking, also known as somnambulism, is a parasomnia that occurs during a specific stage of sleep characterized by reduced consciousness and increased arousal thresholds. It is a complex phenomenon that involves alterations in the normal sleep-wake cycle and the brain's ability to regulate arousal.
**Why the Correct Answer is Right**
Sleep walking typically occurs during the slow-wave sleep stage, specifically during the deep non-rapid eye movement (NREM) sleep stage 3. This stage is characterized by slow delta waves (0.5-4 Hz) and high amplitude, making it difficult to wake the individual. The brain's inability to transition to the lighter stages of NREM sleep or to rapid eye movement (REM) sleep leads to increased arousal and the execution of complex behaviors like sleep walking.
**Why Each Wrong Option is Incorrect**
* **Option A:** Sleep walking is not typically seen in stage 1 NREM sleep, which is characterized by a transition from wakefulness to sleep and is not associated with the deep sleep necessary for somnambulism.
* **Option B:** REM sleep is not typically associated with sleep walking, as it is a stage characterized by rapid eye movements, increased brain activity, and vivid dreams, making it difficult to execute complex behaviors like sleep walking.
* **Option C:** Stage 2 NREM sleep is a lighter stage of sleep characterized by a decrease in delta waves and an increase in slower waves, but it is not typically associated with the deep sleep necessary for somnambulism.
**Clinical Pearl / High-Yield Fact**
The sleep-wake cycle is regulated by the suprachiasmatic nucleus (SCN), which responds to light and dark signals from the environment to synchronize the body's circadian rhythms. Alterations in the SCN or the sleep-wake cycle can lead to sleep disorders like somnambulism.
**Correct Answer:** C. Stage 3 NREM sleep.