The metabolic activities in the bodies of living things follow a certain cycle according to the daily amount of sunlight and the hours at which sunlight can be received. The opening and closing of flowers of some plants, the activation of some animals at night, the adjustment of sleep-wake cycles are the best examples we can give.

In particular, the regulation of hormone secretions in such 24-hour rhythms is called the biological clock. An irregularity in this cycle for any reason also causes the biological clock to be confused.

To give a very general example; The 'jet lag' phenomenon experienced in airplane travels between long distances is a situation that occurs due to the confusion of the biological clock. Because the hormones that reach the highest or lowest levels at certain times in the 24-hour period show a level change at the wrong hours in the new time frame. And until you get used to the new time zone, the body is kind of stunned.