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            Melatonin is a hormone that is secreted by the pineal gland, which is found in the brain.  Its function is to regulate and maintain the body’s circadian rhythm, which is a roughly 24-hour cycle of physiological processes that the body endures.  A large part of this circadian rhythm is regulating a human’s sleep pattern. 

             Melatonin is activated by lack of light and the secretion of this chemical induces drowsiness.  And, of course, light inhibits the secretion of melatonin. 

            After our class discussion on jet lag and the response the body has to traveling through time changes, I thought that this would be a relevant process to discuss.  Because this chemical’s regulation is dependent on light and darkness, abnormal exposure to light can alter the body’s natural clock. This is a perfect example of the Central Nervous System interacting with another major system in the body, this being the endocrine system.

            Interestingly, melatonin can be taken as a dietary supplement that people can use to regulate their sleep patterns.  It is often taken by those who suffer from sleep disorders.