PATHOLOGY

Detailed explanation-1: -Melatonin is a hormone that your brain produces in response to darkness. It helps with the timing of your circadian rhythms (24-hour internal clock) and with sleep. Being exposed to light at night can block melatonin production. Research suggests that melatonin plays other important roles in the body beyond sleep.

Detailed explanation-2: -Darkness prompts the pineal gland to start producing melatonin. View Source, while light causes that production to stop. As a result, melatonin helps regulate the circadian rhythm and synchronize the sleep-wake cycle with night and day.

Detailed explanation-3: -Melatonin appears to have 2 probable interacting effects on the sleep-wake cycle. First, it entrains and shifts the circadian rhythm (process C) in a “chronobiotic” function. Second, it promotes sleep onset and continuity in a “hypnotic” function by increasing the homeostatic drive to sleep (process S).

Detailed explanation-4: -Melatonin is the only known hormone synthesized by the pineal gland and is released in response to darkness hence the name, “hormone of darkness” [10]. Melatonin provides a circadian and seasonal signal to the organisms in vertebrates.