What Is It?
Health Benefits
Dosage Information
Guidelines for Use
General Interaction
Possible Side Effects
Evidence Based Rating Scale

What Is It?

Melatonin is a hormone manufactured and released into the bloodstream by the pebble-size pineal gland nestled deep within the human brain. Surprisingly, scientists only became aware of melatonin's presence in 1958. Children tend to excrete large amounts of this hormone, while older adults produce relatively little. But individual levels of melatonin vary widely. About 1% of the population naturally has quite low levels, while another 1% has levels 500 times above the average.

Melatonin is intimately involved in synchronizing the body's hormone secretions, setting the brain's internal clock and generating circadian rhythms (daily biorhythms). These patterns govern the release of hormones that regulate such body functions as reproduction and digestion. Significantly, melatonin also works around the clock to signal the body, which is sensitive to light cues, when to sleep and when to awaken. Typically, the pineal gland begins excreting melatonin around dusk, rapidly increases its output between 2 a.m. and 4 a.m., and then decreases its output again as daylight appears.

Most melatonin supplements on the market are pure synthetic versions of the hormone, and are practically identical to that which humans produce naturally. Although sold as a dietary supplement in the United States, melatonin is available by prescription only in France and a number of other countries.

Health Benefits

Melatonin is widely used to relieve insomnia and the symptoms of jet lag, two common problems of modern life. Unlike many other sleep aids, melatonin isn't addictive. The hormone may promote health in other ways as well. As an antioxidant, it hunts down and eliminates cell-damaging free radicals, possibly helping to prevent or delay the development of heart disease, cancer and other conditions. When combined with certain cancer drugs, it may destroy malignant cells. Other preliminary findings suggest a possible role in lessening the nerve damage associated with Parkinson's and Alzheimer's diseases, and an ability to prevent strokes and heart attacks by reducing high blood pressure.

Specifically, melatonin may help to:

Treat insomnia. The ability to fall asleep (sleep latency) and stay asleep may get a boost from melatonin supplementation.  Some studies of young and elderly adults have shown that taking a small amount of melatonin before bedtime helps to both hasten sleep and improve its quality. (1-3) These benefits were seen in insomniacs as well as in individuals who struggle with only occasional sleep problems. However, evidence suggests elderly patients with insomnia who are deficient in melatonin, compared to younger adults or children, might benefit most from melatonin supplementation. (4-9) In children with insomnia due to delayed onset of sleep, melatonin seems to shorten sleep latency and increase the duration of sleep. (10)


Ease sleep problems caused by pain or stress. Frequent night-time awakenings can occur as a result of chronic pain or stress. In such situations, melatonin may help by encouraging sounder slumber.


Fight jet lag and restore normal sleep patterns. If you're working a night shift or are traveling across time zones, melatonin supplements may help your body to overcome any disorientation and quickly reestablish a normal sleep pattern. Recent studies of airline personnel and others who travel long distances found that melatonin supplements significantly relieved jet lag symptoms. (11) This was true regardless of whether they were flying eastbound or westbound. However, not all studies have found melatonin to be superior to a placebo for such jet lag symptoms as fatigue, daytime sleepiness and impaired alertness.


Slow the aging process. Animal research indicates that melatonin may be of value in extending life--elderly mice administered the supplement lived 25% longer than their cohorts in one study--although much more investigation is needed before firm conclusions can be made about its value for humans in this regard. Melatonin's antioxidant properties may help to stave off illnesses commonly related to aging, such as heart disease and cataracts. The hormone may boost immune-system function as well, which can weaken with age. (12)


Combat SAD-related depression. A number of people who feel quite normal and energetic in summer become depressed and sluggish in winter, when sunlight is weaker and less abundant. Low melatonin levels may also be present in individuals who react in this way. According to a handful of preliminary studies, such individuals are said to be suffering from SAD (seasonal affective disorder) and may experience a significant improvement in mood if they take several tiny doses (0.1 mg) of melatonin in the afternoon. Study participants who failed to improve took either a large single dose in the morning or no melatonin at all. (13) More studies are needed in this area.


Treat irritable bowel syndrome. Recent research suggests taking melatonin can improve symptoms of irritable bowel syndrome. In one study, IBS patients with poor sleep who took 3 mg of melatonin at bedtime for two weeks reported decreased symptoms of IBS-related abdominal pain and increased rectal pain threshold. However, it did not improve stool frequency or consistency, bloating, mood, sleep, or overall quality of life. (14) Another study of IBS patients who took 3 mg of melatonin at bedtime for eight weeks had decreased severity and frequency of pain; decreased bloating; improved bowel habits; decreased extracolonic symptoms such as headache, heartburn and nausea; and overall improved quality of life. (15)

Note: Melatonin has also been found to be useful for a number of other disorders. For information on these additional ailments, see our Dosage Recommendations Chart for Melatonin.


  • spray
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  • lozenge
  • liquid
  • cream
  • capsule
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Dosage Information

For insomnia: Take 1 to 3 mg immediately before going to bed between 9 p.m. and 11 p.m. Start with the lower dose and gradually increase it over time, if needed. (Older adults may want to start at an even lower dose of 0.3 to 0.5 mg.) In general, the lower dose (1 mg) may prove effective if you have trouble falling asleep, but a higher dose (3 mg) may be necessary if you have difficulty staying asleep.

To prevent jet lag when flying from west to east

--On the day before the flight, take a small dose (about 0.5 mg) of melatonin in the middle of the afternoon.--The day of the flight, take 3 mg two hours earlier than you took the melatonin dose the previous day.

--Upon arrival at your final destination, spend some time in natural sunlight as soon as possible.

--For the first three or four nights of your stay, take 3 mg before bedtime.

To prevent jet lag when flying from east to west:

--On the day before the flight, take a small dose (0.5 mg) in the morning and the same amount again on the morning of your departure.

--Upon arrival at your final destination, wait until morning to take another small dose (0.5 mg, for example) and continue to do so for the next few mornings.

--In the late afternoon of the day that you land, try to spend at least half an hour outside without wearing sunglasses.

For overnight shift work: If you are on a consistent schedule that involves retiring in the morning, take 1 to 3 mg just before going to sleep. If your work hours tend to change, however, consult a health expert for guidance on how and when to take melatonin. 

Be sure to check out our Dosage Recommendations Chart for Melatonin, which lists therapeutic dosages for specific ailments at a glance.

Guidelines for Use

  • To relieve insomnia, it's important to take melatonin at the same time every day.

  • Because precise dosing is so important with a hormone such as melatonin, it's probably not wise to use melatonin in topical (cream or sublingual spray) forms. With repeated applications--and depending on how efficiently your skin absorbs the product--you may end up absorbing more melatonin than you intended.

  • General Interaction

  • Check with your doctor before using melatonin along with a conventional antidepressant. Adverse drug reactions may result.

  • Excessive drowsiness may occur if the hormone is taken along with sedatives, sedating antihistamines, muscle relaxants and narcotic pain relievers.

  • Consult your doctor before considering melatonin if you take prescription corticosteroids. An adverse reaction is likely.


    Note: For information on interactions with specific generic drugs, see our WholeHealthMD Drug/Nutrient Interactions Chart.
  • Possible Side Effects


    Most people feel drowsy within 30 minutes of taking melatonin, an effect that can persist for several hours.


    The development of side effects appears to depend on how much you take and how sensitive you are to the hormone.


    No major problems have been reported in individuals taking relatively conservative doses (3 mg or less).


    Minor side effects have been observed in some people taking up to 8 mg. These include headache, stomach upset, lethargy and disorientation. Some users report a lack of clear-headedness upon waking, and vivid dreams or bad bouts of insomnia. Lower the dosage if any of these reactions occur.


    Still under investigation is whether high doses of melatonin alter the menstrual cycle and can adversely affect a woman's fertility.


    Other risks associated with prolonged use (longer than six months) at any dosage are still being explored.

    Preliminary research in test tubes indicates that melatonin supplements may react with chemicals in the body to alter behavior, such as mood, in unwanted ways. More research is needed to determine if this occurs in humans as well.



    If you take any prescription medication, check with your doctor before starting on melatonin supplements, as potentially hazardous interactions could result.


    When buying melatonin supplements, check the label to confirm that they're synthetically produced and not made from animal glands; these pose the risk of exposure to contaminants.


    Because melatonin can cause drowsiness, avoid driving or handling heavy machinery for several hours after taking it.


    Don't take melatonin if you're pregnant or nursing.


    Women trying to conceive should not take melatonin; at high doses, it appears to work as a contraceptive.


    Children and teenagers produce copious amounts of melatonin and should not take melatonin supplements. 

    Don't take melatonin if you suffer from kidney disease, epilepsy, diabetes, depression, any autoimmune disease, severe allergies, heart disease, leukemia or multiple sclerosis

    Evidence Based Rating Scale

    The Evidence Based Rating Scale is a tool that helps consumers translate the findings of medical research studies with what our clinical advisors have found to be efficacious in their personal practice. This tool is meant to simplify which supplements and therapies demonstrate promise in the treatment of certain conditions. This scale does not take into account any possible interactions with any medication/ condition/ or therapy which you may be currently undertaking. It is therefore advisable to ask your doctor before starting any new treatment regimen.

    Date Published: 04/19/2005
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