Sleep-Wake Disorders — MCQs

Q: Bruxism most commonly occurs during which phase of sleep?

NREM Stage II. **Explanation:** **Sleep Bruxism** is a sleep-related movement disorder characterized by the involuntary grinding or clenching of teeth. **Why NREM Stage II is correct:** While bruxism can occur in any stage of sleep, it is most frequently observed during **NREM Stage II (Light Sleep)**. Statistically, about 80% of bruxism episodes occur during NREM sleep, with the vast majority clustered in Stage II. These episodes are often associated with "micro-arousals"—brief shifts in sleep depth where the sympathetic nervous system activity increases, leading to rhythmic masticatory muscle activity (RMMA). **Analysis of Incorrect Options:** * **REM Sleep (A):** Although bruxism can occur during REM, it is less common. REM-related bruxism is often associated with more severe clinical symptoms and may be linked to obstructive sleep apnea. * **NREM Stage I (B):** This is a transitional phase of very light sleep. While grinding can occur here, the frequency is significantly lower than in Stage II. * **NREM Stage III (D):** Also known as Slow Wave Sleep (SWS) or deep sleep. Parasomnias like sleepwalking (somnambulism) and night terrors typically occur here, but bruxism is less frequent in this stage compared to Stage II. **High-Yield Clinical Pearls for NEET-PG:** * **Treatment of Choice:** The first-line management is usually **stress reduction** and **dental guards (occlusal splints)** to prevent tooth wear. * **Pharmacotherapy:** If severe, **Benzodiazepines** (like Clonazepam) or muscle relaxants may be used short-term. * **Association:** Bruxism is frequently associated with stress, anxiety, and other sleep disorders like Obstructive Sleep Apnea (OSA). * **Key Distinction:** Do not confuse bruxism (Stage II) with **Sleep Terrors/Somnambulism**, which are classic **Stage III (N3)** phenomena.

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