What is melatonin?
Melatonin (N-acetyl-5-methoxytryptamine) is a hormone produced naturally in the brain by the pineal gland from the amino acid tryptophan. The pineal gland (epiphysis) is often called the “third eye” of the body because of its light-transducing ability and by those interested in mystical religions or evolutionary biology. The gland is found resting on the midbrain which is considered the most primitive part of the brain since it controls and regulates vegetative functions of the body that support life without being consciously controlled (endorcrine system, nervous system signals, sexual development). The pineal gland’s main function is to produce and secrete melatonin, commonly known for being a sleep regulator affecting sleep-wake cycles and circadian rhythm.
What are its functions?
Synthetic melatonin supplements are used for a variety of medical conditions and disorders. It is used to treat and ease symptoms from fibromyalgia, pulmonary sarcoidosis (inflammation of lungs), epilepsy, autism, ADHD, autism, prostate cancer, IBS, SAD, menopause, and even protects against sunburns when applied directly to skin. Melatonin is also a powerful antioxidant and plays a major role in metabolism and weight management. Two other less-studied roles of melatonin are as a hormone that stimulates membrane-bound receptors and possibly as a hormone that can activate receptors that turn on/off genes in the DNA strands in a cells nucleus. Melatonin can be found in many tissues of the body including the brain (regulates circadian rhythms), muscles, bone (osteoclastin-bone building, osteoclastic-reduce bone loss), heart and blood vessels (dilates or constricts), reproductive system (suppresses LH, FSH, GnRH and lowers testosterone and sperm production at night, timing and release of female hormones and regulates menstruation cycle), pancreas (less insulin secretion), skin (supports growth and lightens skin pigment,), gut (slows stomach and intestinal contractions, increase digestive enzyme release), and kidneys (reduces inflammation). Melatonin also promotes immune response.
How does it work?
Through a series of enzymatic reactions, serotonin the precursor for melatonin is formed from the amino acid tryptophan and is then released from the pineal gland as the gland senses changes in light and dark cycles. The pineal gland directly senses changes between light and dark, day and night. The skull prevents direct light exposure therefore the pineal gland senses the day and night changes from input through the eyes. Light exposure to the retina is received by fibers of the hypothalamus which then descend down the spinal cord and are first projected to the superior cervical ganglia and then to the post-ganglion neurons ascending back to the pineal gland. This day and night sensory is an important factor to consider in modern society because of many man-made sources of artificial light (light bulbs, TV, computers, etc). Late nights in front of the television or at a movie theatre directly disrupt the pineal gland, therefore causing abnormal melatonin cycles that have unhealthy affects on the whole body. Research has linked many abnormal sleep patterns to a disrupted production of melatonin such as sleep deprivation, shift work, jet lag, sleep apnea, obesity and metabolic disturbances, and many types of insomnia.
What is the Research?
Research on the effect of supplementation of melatonin on sleep disorders is very mixed. Melatonin has been shown to decrease motor activity, induce fatigue and lower body temperature. In contrast other studies have found that when 6 mg melatonin is administered 30 minutes pre-workout, athletes showed reduced free-radical damage, increased antioxidant protection and increased immunity. This is important because of the common feature of athletes who are over-trained and have worsened performance or strength measures due to a lack of sleep. Overall melatonin reduced inflammation in athletes that may provide increased performance. Some studies of weight-management with melatonin supplementation have shown results such as weight reduction, restoring insulin sensitivity, and re-setting the metabolism against over eating. Melatonin also has been shown to directly limit the growth of fat cells (white adipose tissue) in vitro while stimulating growth for brown fat, which actually increases calorie burning for heat production. In studies relating to sleep disorders, research was directly contradictory. Some conclusions stated that melatonin supplementation had no effect on sleep efficiency, quality, total sleep time or percent of time in REM sleep and that short term melatonin use is not effective in most primary sleep disorders. However other studies found melatonin supplementation is effective in advanced wake-sleep rhythms and endogenous melatonin rhythm in delayed sleep phase disorder. Also melatonin was found to extend sleep time in children but not adults.
Should you supplement with melatonin?
Melatonin is fairly inexpensive and shows practical and substantial benefits in many health related areas, including weight reduction and improved performance in athletes. However while melatonin is primarily related to sleep cycles and disorders, the evidence suggesting its effectiveness is inconclusive and contradictory. Melatonin is safe regardless of what the supplementation is for so if you have a few extra dollars go ahead and try it for a period of time. You may not sleep better, but hopefully your body will gain other health benefits from the supplement in the mean time.