Part 3/12:
He explained that, even under constant conditions with no external cues about the time of day, humans possess an intrinsic circadian rhythm, which typically extends slightly beyond 24 hours. Without exposure to natural light, this rhythm drifts out of sync with the solar day, which can be detrimental to survival and performance. Sunlight acts as a cue that entrains the circadian clock precisely to the environment, ensuring our behaviors and physiological processes are aligned with day and night cycles.