Melatonin

Melatonin is the prototypical chronobiotic. Melatonin is used as a chronobiotic to realign the body’s circadian rhythm, but has a narrow window of time when it should be taken; if it is not taken at the correct time, the sleep/wake problem will become even worse. The most effective time to take melatonin is either at dusk or dawn; depending upon when you want to sleep. Other treatments for sleep disorders are altering the sleep/wake pattern until the schedule is normal and bright light therapy.

Melatonin is sold over the counter in the United States. Most European countries make it a prescription drug, and the European Medicines Agency recently approved a slow release preparation sold under the brand name Circadian.

Melatonin has been found to be of value in the treatment of many diseases and disorders. Cancer patients who received melatonin during chemotherapy and radiation had less toxic effects from the treatments, and survival rates and overall ability to function both increased in people with advanced cancer. When melatonin is given prior to surgery, anxiety and pain is decreased, especially in the first day following surgery. Melatonin also helps to readjust and improve the sleep-wake cycle, which is commonly disrupted after surgery.

Melatonin is also effective in alleviating some symptoms of fibromyalgia.

The most compelling evidence now available supports two roles for melatonin in humans: the involvement of nocturnal melatonin secretion in initiating and maintaining sleep, and control by the day/night melatonin rhythm of the timing of other 24-hour rhythms.

Melatonin protects the brain’s neurons, and is effective in preventing the progression of cognitive dysfunction in people with Alzheimer’s disease. Melatonin also helps to reduce “sundowning,” where people affected with Alzheimer’s do not sleep at night due to circadian rhythm disruption. It is estimated that 45% of Alzheimer’s patients suffer sundowning or other sleep disorders. When melatonin is given to people following traumatic brain injury, the amount of brain damage is decreased, along with a reduction in inflammation and the number of infections. At the cellular level, the hormone appears to induce mRNA levels of several antioxidant enzymes. Melatonin increases the effectiveness of the drugs used to treat traumatic brain injury while also decreasing the drugs’ toxic effects. Chemically, melatonin can be classified as a methoxyindole. The formal chemical name is N-acetyl-5-methoxytryptamine.

When used as a treatment for chronic fatigue syndrome, melatonin improves motivation, activity, and concentration and was found to significantly improve fatigue levels. Melatonin levels normally decrease with age, which results in loss of circadian rhythms. Sleep fragmentation in the elderly can be successfully treated with melatonin.

Why would anyone use melatonin for insomnia when other medicines are available? Different drugs work on different neurotransmitter systems in the brain, so it is good to have options. Some patients find benzodiazepine antaogonist drugs to have a paradoxical effect - the drugs make them less likely to sleep. Some with that problem find melatonin to be effective.

Melatonin is being tested for cancer prevention, to treat osteoporosis, and to increase the effectiveness of some medical therapies, while decreasing the toxic effects of the drugs. Scientific research is also being done to explore the effectiveness of melatonin in the treatment of headache disorders, especially migraines and cluster headaches. The hormone may also be part of a nervous system mechanism that is involved with the progression of Alzheimer's disease.

Melatonin has no known food interactions, and no known effects on lab test values.

The typical dosage of 0.5 to 10 mg/day taken at night. Melatonin should not be taken with:

  • anticoagulants (including herbs that act as anticoagulants)
  • antidiabetics
  • benzodiazepines
  • beta-blockers
  • central nervous system depressants (including herbs that act as sedatives)
  • DHEA (dehydroepiandrosterone)
  • immunosuppressants
  • magnesium
  • succinylcholine
  • zinc

There are some people who should not take melatonin; these include children, women who are pregnant or breastfeeding, people who have kidney, liver or heart disease, autoimmune diseases, depression, central nervous system disorders, and Parkinson’s disease. Serious side effects from melatonin have not been reported, but effects from taking melatonin over a long period of time still needs to be studied. Melatonin supplements should be used only under your doctor’s supervision.

Melatonin can be found as a dietary supplement in most health food stores, and is supplied as tablets, extended-release capsules, or in an injectable form when used for cancer treatment. Preparations of melatonin are unregulated at this time; amounts are not standardized, and may be contaminated. Research has shown that melatonin can scavange free radicals, at least in test tubes, and acts as an antioxidant.

Melatonin occurs naturally in some foods, but the amounts are not high enough to influence circadian or circannual rhythm. Serotonin, a neurotransmitter, is the precursor of melatonin, and plays a role in sleep-wake cycle, appetite and gastrointestinal health, mood, depression and obsessive compulsive disorder. There are many foods containing serotonin, but serotonin in food does not cross the blood-brain barrier and is not effective as a chronobiotic in this form.

 



Chronobiotics


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