Melatonin - Overview

Overview

Sleeping is a part of life. It allows the body to rest and repair itself after physical activity. Ruth Winter, writing in The Anti-Aging Hormones: That Can Help You Beat the Clock, stated that "most people need at least seven and a half hours [of sleep] to function adequately and be fully alert the next day, but some may need as little as five while others need nine to ten hours." Lack of sleep can cause a host of problems such as fatigue and poor mood. Thus, it is important to have a normal sleep/wake cycle for good health.

Melatonin is secreted by the pineal gland (shown here), which is located in the middle of the brain. Dr. Frederick Skvara/Visuals Unlimited.
Melatonin is secreted by the pineal gland (shown here), which is located in the middle of the brain. © Dr. Frederick Skvara/Visuals Unlimited.

Melatonin plays an active role in maintaining a regular schedule for sleeping and waking. It induces sleep when it is secreted into the bloodstream by the pineal gland, a pea-sized gland that is part of the endocrine systemThe bodily system made of glands that secrete hormones into the bloodstream to control certain bodily functions.. Darkness stimulates its secretion, while light, both natural and artificial, inhibits it.

The Dracula of Hormones

Melatonin has been called the "Dracula of hormones" because, like the vampire Dracula, it only comes out at night. Usually around 9 P.M., after daylight fades away and darkness arrives, the pineal gland begins releasing melatonin, causing sleepiness and initiating a decline in body temperature. The hormone is continually released throughout the night as the body sleeps until about 9 A.M. the next morning, when it is light again. Peak production occurs approximately between 2 A.M. and 4 A.M.

In the morning, when light hits the retinaA sensory membrane in the eye., messages are sent to the hypothalamusA region of the brain that secretes hormones. in the brain. In the hypothalamus, the messages find the suprachiasmatic (SOO-pruh-ky-uhz-MAH-tik) nucleus (SCN), prompting the SCN to send signals to the glands that control hormones, including the pineal gland. When the pineal gland receives a message from the SCN, it slows down the release of melatonin until darkness comes and it is time to sleep again. Daytime melatonin levels are so small they are usually undetectable. The decrease of melatonin in the morning signals the body temperature to rise, and the body feels awake and alert.

Discovering Melatonin

For centuries, the function of the pineal gland was unknown. This was partly due to the fact that melatonin is created in very small amounts, smaller than any other hormone, and is hard to detect. In the 1950s, Yale University dermatologist Dr. Aaron Lerner was conducting research on skin pigmentation, or color. Thinking the pineal gland may be involved in skin pigmentation, he began the process of trying to isolate a molecule from this gland that he believed may be responsible for lightening skin. In 1958, Lerner was finally successful in isolating a molecule from the pineal gland.

Because the molecule is chemically related to melanin (skin pigment) and serotoninA combination of carbon, hydrogen, nitrogen, and oxygen; it is found in the brain, blood, and stomach lining and acts as a neurotransmitter and blood vessel regulator., Lerner named his discovery melatonin. Though melatonin lightened the skin of frogs, it did not affect the color of the skin of humans. In the end, Lerner did not find a molecule that would help his research, but he did help answer the mystery of the pineal gland. He discovered a very powerful hormone that has helped researchers understand more about the human sleep/wake cycle.

After Lerner's discovery, other scientists began testing melatonin to see what benefits it may have. They found that injecting synthetic (human-made) melatonin into people could cause a tranquilizing effect and induce sleep. From there, more studies were done, and eventually melatonin was made into a dietary supplement that could be self-administered.

The Melatonin Craze

In the mid-1990s, when melatonin supplements became available without a prescription, a frenzy over the possible benefits of taking these supplements occurred. Some called it a "miracle" or "wonder" drug. Many praised it as an immune-booster, a youth serum, a cancer-fighter, and a cure for insomnia.

Various books were written about the wonders of melatonin. The craze eventually died down, and, as of the early twenty-first century, research has not been able to prove or disprove the benefits of melatonin. In 2000, University of Surrey's Josephine Arendt discussed the supplement. As quoted by Elizabeth Cohen in "Study Bolsters Melatonin Sleep Claims" on CNN.com, Arendt stated that "the hype and claims of the so-called miraculous powers of melatonin several years ago did a great disservice to a scientific field of real importance."

Melatonin as a Supplement

In 1994 melatonin became available over the counter as a dietary supplement. Manufacturers claimed melatonin could bring on sleep, ease jet lag, and more. Studies have been conducted and books written on the potential benefits of melatonin, but no one has been able to prove or disprove these claims. Most research suggests that melatonin can help regulate the sleep/wake cycle for conditions such as insomnia and jet lag, as well as problems from shift work (people working at night and sleeping during the day). It has also been regarded as an antioxidantA chemical that neutralizes free radicals (chemicals with an unpaired electron) that can damage other cells. and an immune-booster. Some people believe it also combats aging.