Melatonin is secreted from the pineal gland and regulates the sleep wake cycle, core body temperature, ovulation, and sexual behavior in females, as well as immune and cardiovascular functions. It also has antioxidant, antiinşammatory, and glucose regulatory properties. Melatonin also changes behavior especially in depressed patients or patients who are prone to a psychiatric illness.
External noradrenergic stimuli act on the suprachiasmatıc nuclei and control melatonin secretion, which in turn regulates autonomic functions and daily behaviors by acting as an endogenous synchronizer.
Melatonin, which manages body core temperature, the sleep wake cycle, and gonadal sex steroids, also causes some behavioral problems in case of depression. In bipolar manic patients nocturnal melatonin is found to be higher than in depressed patients because of noradrenergic stimulation.
Melatonin secretion and body core temperature are also closely related. Core body temperature is the lowest when the nocturnal melatonin secretion is high. By controlling core body temperature, melatonin also helps to regulate the body metabolism and glucose utilization.
Ovulation in females is under the control of melatonin. When melatonin is the lowest nocturnally, which causes high core body temperature, it is time for ovulation in females. High core body temperature and low nocturnal melatonin secretion return to normal after the ovulation occurs. It also controls the secretion of sex steroids by its suppressive effect on the gonads. Nowadays some research is working on using it as an oral contraceptive agent.
It also regulates immune functions by acting on T lymphocytes and help organisms to have a high defense against infections, supplying an anti-inşammatory effect and serving as an antitumor agent.
Today it is used specifically for the treatment of sleep disorders such as:
-Advanced sleep phase syndrome
-Delayed sleep phase syndrome
-Circadian rhythm disorders
-Insomnia
-Irregular sleep wake cycle
-Jet-Lag
-Seasonal affective disorders
-REM related behavior disorders