Herbs & Supplements:
Melatonin
Principal Proposed Uses
•
Sleep Disorders, Insomnia, Jet Lag
Other Proposed Uses
•
Reducing Anxiety Before Surgery, Tardive Dyskinesia, Cancer (As an Addition to Conventional Therapy), Epilepsy in Children, Strengthening the Immune System, Preventing Heart Disease, Fighting Aging
Melatonin is a natural hormone that regulates sleep. During daylight, the pineal gland in the brain produces an important neurotransmitter called serotonin. (A neurotransmitter is a chemical that relays messages between nerve cells.) But at night, the pineal gland stops producing serotonin and instead makes melatonin. This melatonin release helps trigger sleep.
The production of melatonin varies according to the amount of light you're exposed to; for example, your body produces more melatonin in a completely dark room than in a dimly lit one.
Melatonin supplements appear to be helpful for people whose natural sleep cycle has been disturbed, such as travelers suffering from jet lag. Melatonin may also be helpful in other forms of insomnia.
Based on early reports that melatonin levels decline with age, the hormone was briefly marketed as a kind of fountain of youth. However, newer evidence suggests that melatonin levels do not decline with age after all.1
Sources
Melatonin is not a nutrient. However, travelers and workers on rotating or late shifts can experience sleep disturbances that seem to be caused by changing melatonin levels.
You can boost your melatonin production naturally by getting thicker blinds for the bedroom windows or wearing a night mask. You can also take melatonin tablets.
Therapeutic Dosages
Melatonin is typically taken half an hour before bedtime for the first 4 days after traveling.
For ordinary insomnia, melatonin is usually taken about 30 minutes to 1 hour before bedtime. To fall asleep on Sunday night after staying up late Friday and Saturday, one study suggests using melatonin 5.5 hours before the desired bedtime.
The optimum dose of melatonin is not clear.
Melatonin is available in two forms: immediate-release (just plain melatonin, also called "quick-release") and slow-release (a special preparation, also called "controlled-release," designed to spread melatonin absorption over many hours). There is some debate as to which one is better; however, evidence from a small double-blind trial in children suggests that quick-release melatonin helps in falling asleep, while slow-release melatonin helps in staying asleep.2
Therapeutic Uses
Reasonably good evidence tells us that melatonin can help people with jet lag or other similar sleep disturbances adjust to a new schedule,3–7,84 although there have been negative studies as well.8,9 Melatonin may also be helpful for many other forms of insomnia, although the evidence isn't entirely consistent.10–31
Melatonin may be useful for individuals who have been using conventional sleeping pills and wish to quit.32
Two double-blind studies found that melatonin was useful for reducing anxiety prior to surgery.33,34
A small double-blind trial suggests that use of of melatonin at a dose of 10mg/day may reduce symptoms of tardive dyskinesia.85
Highly preliminary evidence suggests that melatonin may be useful for some forms of cancer when combined with conventional anticancer treatment.35–38 The explanation for this proposed effect is unknown, and it is quite possible that melatonin could interefere with some types of cancer chemotherapy. We strongly recommend that you consult with your oncologist before taking any herbs or supplements at the same time as cancer treatment.
A preliminary study suggests that melatonin may offer benefits for epilepsy in children.39
Based on theoretical findings rather than solid evidence, it has been suggested that melatonin can boost the immune system, prevent heart disease, and help you live longer.40–43
What Is the Scientific Evidence for Melatonin?
Sleep Disorders
There is good evidence that melatonin can help you fall asleep when your bedtime rhythm has been disturbed. For example, one double-blind placebo-controlled study enrolled 320 people and followed them for 4 days after plane travel. The participants were divided into four groups and given a daily dose of 5 mg of standard melatonin, 5 mg of slow-release melatonin, 0.5 mg of standard melatonin, or placebo.44 The group that received 5 mg of standard melatonin slept better, took less time to fall asleep, and felt more energetic and awake during the day than the other three groups.
Another small double-blind crossover trial found that airplane crews experience improved rest when using melatonin (10mg) as compared to placebo, and equivalent benefits as compared to the drug zopiclone.84 Neither group experienced any impairment in mental function the following morning.
According to one review of the literature, melatonin treatment for jet lag is most effective for those who have crossed a significant number of time zones, perhaps eight.45 One sizeable study on travelers found no benefit,46 but it has been suggested that the change in time zones experienced by these travelers wasn't great enough to require melatonin. However, a small double-blind trial found no benefit even with travel over many time zones.47
Studies of melatonin for the treatment of insomnia related to shift work have yielded relatively unimpressive results.51,56,57,82,83,84
Generally positive result have been seen with the use of melatonin for improving sleep in the elderly.49,51,52,54,55,60However, the results are inconsistent in one way: some found the most improvement in terms of falling asleep, while others identified benefits in different parts of the sleep cycle (such as staying asleep in the middle of the night.)
A 4-week double-blind trial evaluated the benefits of melatonin for children with difficulty falling asleep.61 A total of 40 children who had experienced this type of sleep problem for at least a year were given either placebo or melatonin at a dose of 5 mg. The results showed that use of melatonin significantly helped participants fall asleep more easily. Benefits were also seen in a study of 20 developmentally disabled children with sleep problems.62
Note: The long-term safety of melatonin usage has not been established. Do not give your child melatonin except under physician supervision.
Many individuals stay up late on Friday and Saturday nights, and then find it difficult to get to sleep at a reasonable hour on Sunday. A small double-blind placebo-controlled study found evidence that taking melatonin 5.5 hours before the desired Sunday bedtime improved the ability of participants to fall asleep.63
Benefits were seen in a small double-blind trial of patients in a pulmonary intensive care unit.64 It is famously difficult to sleep in an ICU, and the resulting sleep deprivation is not helpful for those recovering from disease or surgery. In this study of 8 hospitalized individuals, 3 mg of controlled-release melatonin "dramatically improved" sleep quality and duration.
A double-blind placebo-controlled trial of 38 individuals with insomnia and diabetes found significant benefits in sleep quality.65
In addition, a study of 19 individuals with schizophrenia who had disturbed sleep patterns found that 2 mg of controlled-release melatonin improved sleep.66
Blind people often have trouble sleeping on any particular schedule, because there are no "light cues" available to help them get tired at night. A small double-blind placebo-controlled crossover trial found that the use of melatonin at a dose of 10 mg per day was able to resynchronize participants' sleep schedules.67
Some individuals find it impossible to fall asleep until early morning, a condition called delayed sleep phase syndrome (DSPS). Melatonin may be beneficial for this syndrome.68
In addition, individuals trying to quit using sleeping pills in the benzodiazepine family may find melatonin helpful. A double-blind placebo-controlled study of 34 individuals who regularly used such medications found that melatonin at a dose of 2 mg nightly (controlled-release formulation) could help them discontinue the use of the drugs.69
Note: There can be risks in discontinuing benzodiazepine drugs. Consult your physician for advice.
Anxiety Prior to Surgery
Relaxing sedative medications are often used prior to surgery to help reduce the anxiety that often occurs while waiting for surgery to begin. A double-blind placebo-controlled study of 75 women waiting for surgery compared melatonin against the standard drug midazolam.70 Although midazolam was more effective, melatonin was definitely superior to placebo, and patients appeared to like each one equally. One advantage of melatonin was that it did not cause amnesia.
Benefits were also seen in a subsequent double-blind trial of 84 women about to receive anesthesia, conducted by the same researcher.71
Cancer
Melatonin has been used with conventional anticancer therapy in more than a dozen clinical studies. Results have been surprisingly good, although this research must be considered preliminary. For example, a double-blind study on 30 people with advanced brain tumors suggested that melatonin might prolong life and also improve the quality of life.72 Participants received standard radiation treatment with or without 20 mg daily of melatonin. After 1 year, 6 of 14 individuals in the melatonin group were still alive, compared with just 1 of 16 from the control group. The melatonin group also had fewer side effects due to the radiation treatment—a notable improvement in their quality of life.
Improvements in symptoms and a possible reduction of mortality were also seen in other studies.73,74 Melatonin appears to work by increasing levels of the body's own tumor-fighting proteins, known as cytokines.75
Safety Issues
A safety study found that melatonin at a dose of 10 mg daily produced no toxic effects when given to 40 healthy males for a period of 28 days.76 However, this does not prove that melatonin is safe when taken on a regular basis over the long term. Keep in mind that melatonin is not truly a food supplement but a hormone. As we know from other hormones used in medicine, such as estrogen and cortisone, harmful effects can take years to appear. Hormones are powerful substances that have many subtle effects in the body, and we're far from understanding them fully. In fact, according to a preliminary double-blind study, melatonin affects testosterone and estrogen metabolism in men, and may impair sperm function.
Melatonin appears to cause drowsiness and decreased mental attention for about 6 hours after using it, and may also impair balance.77,78 For this reason, you should not drive or operate machinery for several hours after taking it. However, there doesn't appear to be any "hangover" the following day.84
Based on theoretical ideas of how melatonin works, some authorities specifically recommend against using it in people with depression, schizophrenia, autoimmune diseases, and other serious illnesses. One study in postmenopausal women found evidence that melatonin might impair insulin action and glucose tolerance, suggesting that people with diabetes should not use it.79 However, another study found melatonin safe and effective for people with diabetes.80 Because of these contradictions, we suggest that individuals with diabetes seek physican supervision before using melatonin.
Maximum safe dosages for young children, pregnant or nursing women, or those with serious liver or kidney disease have not been established.
View References
Last reviewed August 2002 by Medical Review Board
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