Melatonin is a hormone produced by the pineal gland in the brain. Each day your body secretes melatonin following a daily rhythm. This daily rhythm is synchronized by regular exposure to a 24-hour cycle of light and dark and may serve as a biological timer for the body. Natural secretion of melatonin peaks at night but it does not control sleep. Healthy, young and middle-aged adults will usually secrete between 5 micrograms and 25 micrograms of melatonin each night. This is far less than the amounts commonly found in supplements sold at the health food store, which usually range from 1 to 5 milligrams.
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The use of melatonin to prevent and treat jet lag is backed by clinical studies, according to a review in the April 2011 issue of "Pharmacy and Therapeutics." Using melatonin on the day of travel and for several days thereafter can reduce the number of days required to return to a normal sleeping pattern. A pre-flight dose early in the evening -- taken around bedtime in the destination time zone -- followed by a dose every evening at bedtime for four days after arrival is recommended for travelers going eastbound, according to Drugs.com. Conversely, when traveling westbound, you should take melatonin for four days at night at the desired bedtime after arrival in the new time zone.
Some people use melatonin in the evening to fight insomnia. A few clinical studies using human subjects show that it is more effective than a placebo when used for a short period of time, such as a few days or weeks. Individuals who work the night shift or who swing between a night shift and day shift may also benefit from melatonin prior to sleep. Dosages were taken between 30 and 60 minutes prior to sleep, and researchers found that melatonin may work best for people suffering from insomnia who are over the age of 55. Melatonin has also been found useful in delayed sleep phase syndrome, which is a condition that results in delayed sleep onset as well as sleep disorders in children who have behavioral, developmental or intellectual delays.
The University of Maryland Medical Center reports that other possible uses for melatonin -- for which solid clinical evidence is lacking, but some case studies support -- include treating age-dependent body temperature rhythms, more commonly known as hot flashes in menopause, as well as age-related macular degeneration and preoperative anxiety. Based on limited human studies, melatonin has been found effective as an anti-inflammatory and has been used as an adjunct of treatments in individuals with advanced stage cancers, including brain, breast, gastric, liver, lung, pancreatic and testicular cancer. Limited information is also available about the use of melatonin in chronic fatigue syndrome, cognitive enhancement and in the control of blood sugar in individuals who suffer from diabetes.
Melatonin can interact with other medications. These medications include antidepressants, antipsychotics, benzodiazepines, high blood pressure medications, blood thinners, nonsteroidal anti-inflammatory pain medications, steroids and tamoxifen, a chemotherapy drug used in the treatment of breast cancer. Melatonin also interacts with caffeine, tobacco and alcohol, all of which lower the levels of melatonin in the body. According to Drugs.com, adverse reactions can also include depression, dizziness, bedwetting, headache and nausea. At this time, little or no evidence suggests any major toxicity of melatonin.