Melatonin, also known chemically as N-acetyl-5-methoxytryptamine, is a naturally occurring compound found in animals, plants, and microbes. In humans and other higher animals, melatonin is produced by pinealocytes in the pineal gland (located in the brain, but outside the blood-brain barrier), also in the retina, lens, GI tract, and other tissues.
Production of Melatonin by the pineal gland is under the influence of the SCN (suprachiasmatic nuclei) of the hypothalamus, which receives information from the retina about the daily patterns of light and darkness.
Roles as we know in the human body
Melatonin is responsible for signaling part of the system that regulates the sleep-wake cycle by chemically causing drowsiness and lowering the body temperature.
Production of melatonin by the pineal gland is inhibited by light and permitted by darkness. For this reason melatonin has been called “the hormone of darkness”.
Besides being our biological clock, melatonin also exerts a powerful antioxidant activity. Studies have found that in many lower life forms melatonin serves only this purpose. Melatonin is an antioxidant unlike many that can easily cross cell membranes and the blood-brain barrier.
While it is known that melatonin interacts with the immune system, the details of those interaction are unclear. Some studies suggest that melatonin might be useful fighting infectious diseases and potentially in the treatment of cancer.
Some people under the influence of supplemental melatonin sleep aid report vivid dreaming. This occurs because vivid dreams occur when in REM sleep (rapid-eye-movement sleep) and do to the increase of melatonin the dream activity rises. Many psychoactive drugs, such as LSD (lysergic acid diethylamide) increase melatonin synthesis. This result is why people that take a high dose of melatonin will dramatically increase REM sleep and dream activity.
Individuals with autism may have lower than normal levels of melatonin. A study conducted, found that unaffected parents of individuals with ASD also have lower melatonin levels. These deficits are associated with low activity of the ASMT gene, which encodes the last enzyme of melatonin synthesis.
Melatonin as a Sleeping Aid
The use of melatonin as a sleep supplement can entrain the circadian clock to its normal state and can have beneficial effects when treating some forms of insomnia. The Primary motivation for the use of melatonin may be as a natural aid to better sleep. Incidental benefits to health and well-being may accumulate due to melatonin’s role as an antioxidant and its stimulation of the immune system and several components of the endocrine system.