Circadian Rhythm

All species have a timing mechanism, or 'clock,' that controls periods of activity and inactivity. These clocks are known as circadian rhythms and refer the cycle of physiological and biological processes that fluctuate on a roughly 24-hour timetable. These processes include sleep-wake cycles, body temperature, blood pressure, and the release of hormones. You’ve probably noticed these tendencies yourself, feeling more energetic and alert during peak periods of the day and more lethargic and run-down at other times of the day.

Disruptions to the circadian rhythm can cause problems with the sleep-wake cycle.