Which of the following are seen in deep NREM sleep:
**Core Concept**
Deep NREM (Non-Rapid Eye Movement) sleep is characterized by high-amplitude, low-frequency **delta waves** on electroencephalography (EEG). This stage is crucial for restorative sleep, including the repair and growth of tissues.
**Why the Correct Answer is Right**
Deep NREM sleep is associated with specific physiological changes, including decreased **cortical activity**, reduced **metabolic rate**, and increased **parasympathetic tone**. During this stage, the body repairs and regenerates tissues, builds bone and muscle, and strengthens the immune system.
**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because it is more commonly associated with REM sleep.
**Option B:** Incorrect as it is not a characteristic feature of deep NREM sleep.
**Option C:** Incorrect because it is typically seen in lighter stages of NREM sleep or wakefulness.
**Option D:** Incorrect as it is not a defining feature of deep NREM sleep.
**Clinical Pearl / High-Yield Fact**
Deep NREM sleep is essential for physical recovery and is often referred to as **restorative sleep**. Disruptions in deep NREM sleep can lead to impaired physical recovery and decreased immune function.
**Correct Answer:** D. Slow delta waves and restorative sleep.