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What is melatonin and how does it work? (Benefits and Usage)

“Melatonin use among adults in the United States more than doubled between 2007 and2012,” with over 3 million people currently taking the supplement.

This substance has recently gained attention as the subject of new research for applications that include more than just sleep health.

But what is it, exactly?

What is melatonin?

Melatonin is a hormone which, when released into the bloodstream, leaves you feeling less awake and alert as it promotes the transition from wakefulness to sleep in both your brain and your body.We naturally make our own melatonin, but its release into the bloodstream can be disrupted by external factors. Also, for some people, melatonin can be in poor supply.

Melatonin has other jobs besides helping us to fall asleep. It is also a master hormone regulator and a critical player in regulation of the menstrual cycle and the digestive process. New research continues to show other applications for using melatonin that have moved far beyond the sleep-wake process.

Kinds of melatonin

Melatonin is either endogenous (natural, made by the body) or exogenous (synthetic, manufactured as a pill).

Endogenous melatonin

The pineal gland is a tiny organ located just above the center of the brain that is responsible for releasing this natural hormone into the bloodstream.

Endogenous melatonin is not generally released until the sun goes down and ambient light dims, as the pineal gland takes its direction from measures of light exposure to the eyes. Signals through the optic nerve send messages to the brain which then commands the release of natural melatonin.

When night falls, exogenous melatonin is released by the pineal gland for a period of about 12 hours until the light of day forces it to taper back its levels in the morning.

Our cells also manufacture their own supplies of endogenous melatonin to carry out specific cellular tasks.

Exogenous melatonin

This synthetic form of melatonin is a hormonal substance that can be found naturally in many foods; therefore, it is not FDA regulated like other hormones, but is considered a dietary supplement. It is manufactured by processing the pineal glands of cows.

Exogenous melatonin can be found on grocery store and pharmacy shelves without a prescription. Its chemical is N-acetyl-5-methoxytryptamine. However, many melaton informulations include herbs and other supplements, which should also be listed on the label.

Melatonin and the circadian system

Our circadian rhythms rely on exposure to light and other time cues (known as zeitgebers ) to keep our bodies in proper balance.

When melatonin is released into the bloodstream at night (naturally, or by way of a supplement), it can help keep the so-called “body clock” on track for sleep.

While many people have no trouble falling asleep at night, others struggle, and turn to synthetic melatonin to achieve this goal.

How exogenous melatonin supports your rhythms

Some studies show that the use of exogenous melatonin can reduce the time it takes to fall asleep and may decrease the number of nighttime awakenings in some people.

Other studies show that while sleep onset may improve after taking exogenous melatonin, it doesn’t not necessarily lead to increases in total sleep time. Other researchshows only placebo effects with synthetic melatonin when used for sleep problems.

However, a great deal of research is currently underway to measure its effectiveness as a long-term treatment for many kinds of sleep disorders, including:

  • insomnia disorders

  • delayed sleep phase disorder ( especially in teens )

  • advanced sleep phase disorder

  • non-24 sleep-wake disorder

  • shift work disorder

  • jet lag disorder

Blind people, who often suffer from circadian rhythm sleep disorders, may also benefit from synthetic melatonin if their brains are unable to perceive light.

Using melatonin

Johns Hopkins sleep expertLuis F. Buenaver PhD CBSM suggests that exogenous melatonin is safe to take nightly for up to two months.After that, stop and see how your sleep is, he says.

Buenaver recommends that people turning to melatonin to help with sleep onset try to find ways to enhance its effectiveness. Mostly, this means practicing good sleep hygiene, especially by avoiding exposure to bright light at night (from handheld electronic devices and LED light sources, in particular).

He also suggests getting a good dose of bright natural light first thing in the morning to ensure circadian rhythms are set to a normal pattern during the beginning of the day.

Timing and dosage of exogenous melatonin is also critical to its success.


Circadian rhythms rely on timing for the regulation of many of our rhythms, not just for sleep, but for other processes in the body (such as digestion). An intelligent use of synthetic melatonin requires taking an appropriate dose at the appropriate time.

For people using it for insomnia, this means within two hours of their desired bedtime, but for someone with jet lag or shift work disorder, they will need to take it at different times depending on their misalignment with local time of day.

Taking exogenous melatonin at times that are inappropriate to your particular sleep concern can have the unwanted effect of resetting your biological rhythms in a way that could actually interfere with future sleep or wakefulness patterns.


The University of Maryland Medical Center suggests that people who choose to supplement with synthetic melatonin keep their dosage as close to their body’s own natural production as possible, which is less than 0.3mg daily. Start with the lowest dose possible (below this amount) and work your way up as needed.

Check labels carefully. Many formulations greatly exceed these dosage suggestions.

Also, keep an eye out for additional herbs and supplements that might be part of the formulation as they may have side effects or could interact with other drugs you are taking. This could also have an adverse effect on your sleep health.

From the National Sleep Foundation comes this caveat:

“Because it is not categorized as a drug, synthetic melatonin is made
in factories that are not regulated by the FDA. Listed doses may not be
controlled or accurate, meaning the amount of melatonin in a pill you
take may not be the amount listed on the package. Most commercial
products are offered at dosages that cause melatonin levels in the blood
to rise to much higher levels than are naturally produced in the body.
Taking a typical dose (1 to 3 mg) may elevate your blood melatonin
levels to 1 to 20 times normal.

The risks of using melatonin

Side effects

Keep in mind that preparations of exogenous melatonin often suggest higher dosages which can lead these side effects:

  • irritability

  • vivid dreams and nightmares

  • anxiety

  • daytime sleepiness

  • stomach cramps

  • dizziness

  • headache

  • decreased libido

  • breast enlargement in men ( gynecomastia )

  • reduced sperm count

Research shows that exogenous melatonin supplements may:

  • raise blood-sugar levels

  • worsen depression

  • be especially disruptive to people with other hormone imbalance problems

Possible drug interactions

Exogenous melatonin has also been shown to have negative interactions with certain prescription drugs like:

  • blood thinners

  • immunosuppressants

  • antidepressants

  • nonsteroidal anti-inflammatories (NSaids)

  • blood pressure medications

  • beta blockers

  • corticosteroids

  • diabetes medications

  • birth control pills

Caffeine, tobacco, and alcohol can also reduce levels of naturally produced melatonin.

Finally, despite the fact that the NCCIH reported that “melatonin use by children rose significantly[in 2012)], up from 0.1 percent in 2007,” it is not recommended for use in children under the age of 12 due to concerns about seizures and limited evidence of its overall safety for this age group.

If you are concerned about taking melatonin, talk to your sleep specialist; they can help guide you with timing and dosage.


Johns Hopkins Medicine
Mayo Clinic
National Center for Complementary and Integrative Health (NCCIH)
National Sleep Foundation
University of Maryland Medical Center

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