BodyClock

昼夜节律是遵循一个大致24小时为周期，在人体内的变化。

The rhythm has an endogenous free-running period that lasts approximately 24 hours. The rhythm persists in constant conditions, (i.e., constant darkness) with a period of about 24 hours. Health problems can result from a disturbance to the circadian rhythm. Circadian rhythms also play a part in the reticular activating system, which is crucial for maintaining a state of consciousness. A reversal in the sleep–wake cycle may be a sign or complication of uremia, azotemia and acute renal failure.