This refers to the 24-hour cycle that influences the various physiological processes that take place within the human body. Among others, the circadian rhythm most commonly determines the hours that a human being is asleep or awake during a day. Other important things like the metabolic rate, body temperature, blood pressure, and the secretion of various hormones are also influenced by the circadian rhythm. It is believed that disturbances to the circadian rhythm, which is seen by some scientists as an adaptation to conditions prevalent on earth over a long period of time, due to changes in a person’s lifestyle, for instance, can lead to adverse effects on the human body.