Biological rhythms are the regular fluctuations in our bodily processes and in consciousness over time. Many of these fluctuations occur over a course of a single day and are therefore known as circadian rhythms (from the Latin words “around” and “day”).
Most people are aware of their fluctuations in energy level, alertness and mood over the course of a day, and research findings indicate that such shifts are closely related to the changes in underlying bodily processes. In addition, the circadian rhythms seem to shift with age; as people grow older, their peeks often tend to occur earlier in the day. These cyclic changes in our bodily processes –are related to task performance. In general, people do their best work when body temperature and other internal processes are at or near their personal peaks.
SUPRACHIASMTIC NUCLEUS (SCN): This structure located in the hypothalamus, also known as a biological clock, plays a major role in the circadian rhythms. It appears that individual cells in this structure tick-or in other words keep track of time. This biological clock responds to light. Morning resets our biological clock, synchronizing it with the external world. This is necessary or else our clock seems to operate in a 25 hour cycle; thus if it were not reset each day, our internal biological rhythms would get farther and farther out of synch with the world around us.
PINEAL GLAND: For long term biological rhythms, such as mating season and hibernation another structure in the mid brain, the pineal gland, seems to play an important role. This gland which sits on he top of the mid brain, just in front of the cerebellum, secretes a hormone known as melatonin. It’s connected to SCN and secretes melatonin in response to input by SCN.
Melatonin influences several structures in brain, regulating the production of hormones, affecting many basic physiological processes. It is secreted mostly at night; so when nights are long, larger amounts are secreted. High levels of melatonin seem to trigger hibernation in many species. When days get longer, lower level of melatonin gets many species to enter into their summer phase or spring phase; they become more active and begin to seek a mate.
