Polysomnography of a healthy 20-year-old man correlates his episodic GH surges with a specific sleep stage. GH pulse amplitude is maximal during which stage?

• A REM sleep
• B Sleep onset latency while awake
• C Stage N1 transitional sleep
• D Stage N3 slow wave sleep ✓

Explanation

The largest GH pulse of the 24-hour cycle occurs shortly after sleep onset and coincides with slow wave sleep (N3). Deepening slow wave activity is coupled to reduced somatostatin tone and increased GHRH drive from hypothalamic arcuate neurons, producing a high amplitude secretory burst. REM sleep is associated with low GH output. This coupling underlies why poor deep sleep in adolescents impairs somatic growth.

Reference: Ganong's Review of Medical Physiology, 26th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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