MelatoninMelatonin is a hormone produced by the pineal gland, a small gland in the brain, that varies with the body's sleep cycles. In humans and other diurnal animal species, melatonin secretion happens during normal sleep hours, in contrast to nocturnal animals which are at the peak of their activity while producing melatonin. Melatonin is sometimes called "the hormone of the night." The melatonin cycle is roughly the opposite of the body temperature cycle. At 4 am, the temperature is at its lowest and the melatonin level is at its highest.
Very small amounts of melatonin are found in foods such as meats, grains, and vegetables. How it actually causes sleepiness is unknown as are the details of its metabolism and excretion from the body. Melatonin is sold as a supplement in some drug stores and alternative health stores. It may help some people, and it causes few side effects. However, the manufacture and marketing of melatonin supplements is unregulated, so the amount and quality of melatonin in supplements made by different manufacturers may not be the same. Consequently, most doctors do not prescribe or recommend melatonin. Normal melatonin The physiological roles of melatonin are still unclear despite almost 50 years of research. Elevated melatonin levels (either natural or from taking melatonin tablets) are associated in humans with effects including increased sleepiness, reduced core temperature, increased heat loss and other generally anabolic physiological changes. This suggests that melatonin pills can make people sleep better or longer. They are not as strong as prescription sleep aids, however, and the US Food and Drug Administration has never actually approved melatonin for circadian rhythm sleep disorders. A 2005 meta-analysis (an analysis of other studies on melatonin) concludes that melatonin treatment reduces sleep onset latency, increased sleep efficiency, and increased total sleep duration. However, the average increase in sleep duration was only 13 minutes. The Agency for Healthcare Research and Quality conduced a meta-analysis and said there was a "substantial amount of heterogeneity across studies of melatonin." Substantial amount of heterogeneity meaning there are no clear answers. Another meta-analysis showed that only a small dose of melatonin (about 0.3 milligrams) is necessary for a restful effect. However, that commercially available melatonin pills contain 10 times the effective amount. Melatonin has been used to adjust the circadian system in people with jetlag, shiftwork, delayed sleep phase syndrome, and some sleep problems of the elderly. No long-term safety data exist, and the optimum dose and formulation for any application remains to be clarified. Some blind people use melatonin to help them sleep on the same cycle as sighted people (who have visual sunlight cues to adjust their cycles). It seems to work in about half of people who try it. Blind teens are advised to not use melatonin because of concerns that it might affect puberty. Large amounts of melatonin are known to inhibit ovulation. The chemical name for melatonin is N-acetyl-5-methoxytryptamine. Here's the structure, for chemistry buffs:
Sleeping with the lights on causes cancer! No, but there was a headline a few years ago saying "Sleeping with lights on might trigger cancer through melatonin suppression." Sleeping with the lights on lowers the amount of melatonin in the bloodstream. Melatonin is an antioxidant and so might contribute to a lower risk of cancer. It also inhibits the growth of tumors. And there are overall health benefits to going through a full circadian cycle, which includes a period of darkness. So there might be some benefit to sleep without the lights on. A bit of an exaggeration to say sleeping with the lights on "triggers" cancer. There has been concern that the shift work leads to higher rates of cancer. However an epidemiological study at Ohio State University found no link. Melatonin and sleep in aging population. Read about valerian, an herb used to help people sleep.
It's interesting that he was a dermatologist and focued most of his research on pigment disorders. Melatonin is a pigment, of course, but it is mostly known for its role in the circadian cycle.
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newsStudy Links Children's Sleep Problems to School Problem Scientists working on sleep/wake equation Average sunrise time predicts depression prevalence Study says therapy better than pills in treating sleep-onset insomnia
"Sleep hath seized me wholly" (William Shakespeare – Cymebline)
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