A patient undergoing polysomnography shows reduced slow-wave sleep after prolonged exposure to bright light late in the evening. Which mechanism most likely explains this?

💡 Explanation

Bright light exposure inhibits melatonin secretion via the suprachiasmatic nucleus; because melatonin normally promotes sleep initiation and maintenance, its suppression diminishes sleep pressure, thereby decreasing slow-wave sleep. Therefore, reduced sleep pressure occurs, rather than cortisol, ghrelin, or body temperature directly enhancing or inhibiting sleep.

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