This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Physiology
[{'content': 'In which phase of sleep, does the bruxism occur? \nSelect and explain. \nA. NREM 2, B. NREM 3, C. REM sleep, D. NREM 4', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Bruxism occurs in both stage I and stage II. But more common in stage II.\nNote:\xa0OSA is not associated with a reduction in total sleep time, but individuals with OSA experience a much greater time in stage 1 NREM sleep (from an average of 10% of total sleep to 30–50%) and a marked reduction in slow-wave sleep (stages 3 and 4 NREM sleep). The pathophysiology of OSA includes both a reduction in neuromuscular tone at the onset of sleep and a change in the central respiratory drive.\nReference: Ganong’s Review of Medical Physiology T W E N T Y - F I F T H\xa0 \xa0E D I T I O N page no 276', 'role': 'assistant'}]