Question

Julie is more alert in the morning, and her brother Jack is more alert in the afternoon. This difference stems from a difference in the siblings'...

A) Circadian rhythms
B) Sleep patterns
C) REM sleep cycles
D) Melatonin levels

Answer 1

Julie and Jack's different periods of alertness are due to differences in their circadian rhythms, which are natural, internal processes regulating sleep-wake cycles and affected by environmental light.

Step-by-step explanation:

The difference in alertness between Julie, who is more alert in the morning, and her brother Jack, who is more alert in the afternoon, is likely due to a difference in their circadian rhythms. Circadian rhythms are daily cycles of behavior including sleeping and waking, which are influenced by the brain's internal clock in the suprachiasmatic nucleus (SCN) and external environmental cues like light. While sleep patterns, REM sleep cycles, and melatonin levels can also influence sleep-wake cycles, they are constituents of or influenced by the overarching circadian rhythms that dictate the inherent preference for morning or evening alertness.