Circadian Rhythm or Biological Clock

Circadian rhythms or biological clock are the natural physical, mental, and behavioral oscillations that we experience roughly every 24 hours (also called diurnal rhythms). The body’s complex systems are tied to the night-and-day cycle, affecting sleep patterns, hormone release, appetite and digestion, and temperature. Daily patterns that occur within (endogenous) are regulated by our biological or circadian clock, but adjust to the local environment (entrainment) by external cues (zeitgebers), which include light, temperature, and other molecular cycles. Our biological clock’s primary function is to rhythmically synchronize processes to maximize our health and fitness. In clinical settings, abnormal circadian rhythms are known as a circadian rhythm sleep-wake disorder, frequently seen in mood disorders, especially bipolar disorder.