Biological process regulating sleep-wake patterns.

Biological process regulating sleep-wake patterns.

• A. REM
• B. Fluid Rounds
• C. Circadian Cycle
• D. NREM Sleep

Answer: (C)

The circadian cycle is the body’s 24-hour clock that coordinates when we feel awake and when we feel sleepy. It responds to light and dark cues—light information reaches a brain region called the suprachiasmatic nucleus, which then helps regulate hormone release (like melatonin at night and cortisol in the morning), body temperature, and alertness. REM and NREM are stages that occur during sleep, not the regulator of the sleep-wake pattern. Fluid rounds are unrelated to sleep regulation. In practice, the circadian cycle best explains why our sleep-wake times alternate and why disruptions (like jet lag or aging) disturb sleep; encouraging regular schedules and morning light can help align this cycle.

The circadian cycle is the body’s 24-hour clock that coordinates when we feel awake and when we feel sleepy. It responds to light and dark cues—light information reaches a brain region called the suprachiasmatic nucleus, which then helps regulate hormone release (like melatonin at night and cortisol in the morning), body temperature, and alertness. REM and NREM are stages that occur during sleep, not the regulator of the sleep-wake pattern. Fluid rounds are unrelated to sleep regulation. In practice, the circadian cycle best explains why our sleep-wake times alternate and why disruptions (like jet lag or aging) disturb sleep; encouraging regular schedules and morning light can help align this cycle.