What Does Melatonin Do, and How Does It Work?

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What is melatonin?

Melatonin is a hormone that your body makes naturally (1).

It’s produced by the pineal gland in your brain but also found in other areas, such as your eyes, bone marrow, and gut (2).

It’s often called the sleep hormone, as high levels can help you fall asleep.

However, melatonin itself won’t knock you out. It simply lets your body know that it’s nighttime so that you can relax and fall asleep more easily (3).

Melatonin supplements are popular among people with insomnia and jet lag. You can buy melatonin supplements without a prescription in many countries.

In addition to its benefits for sleep, this hormone has strong antioxidant and anti-inflammatory effects (1).

Summary

Melatonin is a hormone that your pineal gland makes naturally. It helps you fall asleep by calming your body before bed.

How does melatonin work?

Melatonin works in tandem with your body’s circadian rhythm (1).

In simple terms, the circadian rhythm is your body’s internal clock. It lets you know when it’s time to:

  • sleep
  • wake
  • eat

    • Melatonin also helps regulate your body temperature, blood pressure, blood glucose, body weight, and levels of some hormones (1, 4).

    Your melatonin levels start to rise when it’s dark outside, signaling to your body that it’s time to sleep. They then decrease in the morning, when it’s light outside, to promote wakefulness (5).

    Melatonin also binds to receptors in your body to help you relax.

    For instance, it binds to receptors in your brain to reduce nerve activity. It can also reduce levels of dopamine, a hormone that helps you stay awake, and is involved in some aspects of the day-night cycle of your eyes (6, 7).

    Although melatonin’s exact mechanisms are unclear, research suggests that these processes may help you fall asleep.

    Conversely, daylight modulates melatonin production, which is one way your body knows it’s time to wake up (8).

    Because melatonin helps your body prepare for sleep, people who don’t make enough of it at night can have trouble falling asleep.

    Many factors may cause low melatonin levels at night, such as alcohol consumption, smoking, caffeine consumption, shift work, aging, certain medications, and exposure to too much light at night — including blue light (9, 10).

    Taking a melatonin supplement may help counter low levels and normalize your internal clock.

    Summary

    Melatonin works closely with your body’s circadian rhythm to help prepare you for sleep. Melatonin levels rise at night in response to darkness and decrease in the morning in response to light.

    Taking melatonin for sleep may help

    Strong evidence suggests that taking melatonin before bed decreases sleep latency — the time it takes you to fall asleep — while increasing total sleep time (11, 12, 13).

    A review of 11 studies demonstrated that taking melatonin before bed decreased sleep latency by almost 3 minutes and increased total sleep time by about 30 minutes, compared with a placebo (11).

    Another analysis of 23 studies in people with disease-related sleep disorders found that melatonin significantly reduced sleep disturbances and sleep latency while increasing sleep duration and quality (13).

    Although this analysis concluded that melatonin wasn’t helpful for improving sleep in people with mental disorders or brain diseases such as Alzheimer’s disease, other studies have shown otherwise (14, 15, 16).

    Additionally, melatonin may counteract jet lag, a temporary sleep disorder.

    Jet lag occurs when your body’s internal clock is out of sync with a new time zone. Shift workers may also experience jet lag symptoms because they work during hours that are normally used for sleep (17).

    Melatonin may help reduce jet lag by syncing your internal clock with the time change (18).

    For instance, an analysis of 11 studies in people who traveled through 5 or more time zones found that melatonin was likely effective at reducing the effects of jet lag (19).

    Before trying melatonin, though, it’s best to implement healthy sleep habits such as establishing a consistent sleep schedule, limiting alcohol and caffeine consumption, and reducing your exposure to light and electronic devices before bed.

    Summary

    Research indicates that melatonin may help you fall asleep faster. In addition, it may help people with jet lag get to sleep.

    Additional melatonin health benefits

    In addition to improving sleep, melatonin may provide other health benefits.

    May support eye health

    Healthy indole-derived melatonin levels may support eye health.

    That’s because this hormone has powerful antioxidant effects that may lower your risk of eye diseases, such as age-related macular degeneration (AMD) (20).

    Indeed, a review concluded that melatonin supplements may reduce AMD by neutralizing free radicals and decreasing inflammation (21).

    May help treat acid reflux and GERD

    Melatonin may help alleviate acid reflux and gastroesophageal reflux (GERD) by protecting the lining of your esophagus — the tube that connects your throat and stomach — against irritants such as acid, alcohol, and nonsteroidal anti-inflammatory drugs (22).

    For example, one study showed that taking melatonin inhibits an enzyme system that damages the esophageal epithelial barrier, which is responsible for protecting deeper layers of your esophagus from damage.

    Damage to the esophageal epithelial barrier is known to cause acid reflux and GERD and may eventually lead to more severe health complications such as cancer (23, 24).

    Still, further research is necessary.

    May reduce symptoms of tinnitus

    Tinnitus is a condition characterized by ringing in the ears. It’s often worse when there’s less background noise, such as when you’re trying to fall asleep (25).

    Interestingly, researchers suggest that taking melatonin may help reduce symptoms of significant tinnitus and improve sleep (26).

    A review of five studies concluded that melatonin use alone or alongside tinnitus medications may manage this condition while improving sleep. However, these studies were of low quality, limiting the strength of the review’s findings (27).

    May alleviate migraine attacks

    A migraine attack is a recurring type of headache that causes severe, throbbing pain or a pulsing sensation, often on the side of your head.

    Several prescription drugs help treat migraine, but melatonin may also offer relief due to its ability to inhibit pain sensations (28).

    In a review of 11 studies, taking melatonin significantly reduced migraine severity and frequency compared with a placebo in both children and adults, but with varying effectiveness (28).

    A different review of 25 studies found similar results, suggesting that taking 3 mg of melatonin at bedtime reduced migraine frequency in adults (29).

    Summary

    Melatonin may support eye health, ease tinnitus symptoms, treat acid reflux and GERD, and alleviate migraine attacks, but stronger evidence is needed for these uses.

    How to take melatonin

    If you’re considering trying melatonin for insomnia, starting with a low dose supplement is recommended.

    For instance, start with 0.5–1 mg 30 minutes before going to bed. If that doesn’t seem to help you fall asleep, try increasing your dose to 3–5 mg.

    Taking melatonin in excess of 5 mg is unlikely to help you fall asleep faster. The goal is to find the lowest dose that helps you sleep.

    However, it’s best to follow the instructions that come with your supplement and talk with a healthcare professional before adding OTC melatonin to your routine.

    Because melatonin comes in different forms, you may also want to consult a doctor or pharmacist about the best form for you.

    Melatonin is widely available in the United States. You’ll need a prescription for melatonin in other places, such as the European Union and Australia (30).

    Summary

    If you want to try melatonin, start with 0.5–1 mg 30 minutes before bed. However, it’s a good idea to consult a healthcare professional before using melatonin.

    Melatonin side effects

    Current evidence suggests that melatonin supplements are safe, nontoxic, and not addictive for either children or adults (1, 31, 32).

    Supplementing long term is also likely safe. Studies have found no significant adverse events associated with daily melatonin intake in dosages of 2–10 mg for up to 3.5 years (31).

    Unlike other hormones, no evidence suggests that taking melatonin affects your body’s natural ability to make its own.

    However, several minor, short-lived side effects of melatonin supplements have been reported. These include (1, 31, 32):

  • daytime sleepiness
  • fatigue
  • dizziness
  • headaches
  • nausea
  • a cold feeling
    • Summary

    Current studies show that melatonin is safe, nontoxic, and not addictive. However, studies have reported minor side effects such as dizziness, nausea, and daytime sleepiness.

    Melatonin interactions

    Despite its relatively strong safety profile, melatonin may interact with a variety of medications by either affecting their effectiveness or increasing the risk of side effects.

    Medications that melatonin may interact with include (1, 31, 32, 33, 34, 35):

  • sleep aids or sedatives
  • blood thinners
  • anticonvulsants
  • blood pressure medications
  • antidepressants
  • oral contraceptives
  • diabetes medications
  • immunosuppressants

    • If you have a health condition or take any of the above medications, it’s best to talk with your doctor before starting to use melatonin.

    Melatonin may also interact with alcohol. Some research suggests that moderate to heavy alcohol use reduces melatonin levels and thus disrupts sleep quality, though results are mixed (36).

    Low levels of melatonin — and related persistent sleep problems — have been associated with alcohol use disorder (AUD) and an increased risk of relapse in people trying to abstain from alcohol (36).

    As such, melatonin supplements may play a critical role in preventing and treating AUD, as well as reduce oxidative stress and inflammation caused by heavy, frequent alcohol intake (36, 37).

    Summary

    Melatonin may interact with medications used to treat common health conditions such as high blood pressure and diabetes. Drinking moderate to high amounts of alcohol before bed may also decrease your melatonin levels and therefore affect sleep.

    Melatonin and pregnancy

    Your natural melatonin levels are important during pregnancy. In fact, melatonin levels fluctuate throughout pregnancy (38, 39).

    During your first and second trimesters, the nighttime peak of melatonin decreases.

    However, as your due date approaches, melatonin levels begin to rise. At full term, melatonin levels reach a maximum. They return to prepregnancy levels after delivery (39).

    When you’re pregnant, melatonin is transferred to the developing fetus, where it contributes to the development of circadian rhythms and both the nervous and endocrine systems (38, 40).

    Melatonin also appears to protect the fetal nervous system. It’s believed that this hormone’s antioxidant effects safeguard the developing nervous system from damage due to oxidative stress (40).

    While it’s clear that melatonin is important over the course of a pregnancy, few studies have examined melatonin supplementation during pregnancy (31, 32, 41).

    As such, taking melatonin supplements during pregnancy is not recommended (1).

    Summary

    Melatonin levels change throughout pregnancy and are important for the developing fetus. However, because research in this area is lacking, supplementing with melatonin during pregnancy is discouraged.

    Melatonin and babies

    During pregnancy, melatonin is transferred to the developing fetus. However, after birth, a baby’s pineal gland begins making its own (42).

    In babies, melatonin levels are lower during the first 3 months after birth. They increase after this period, likely due to the presence of melatonin in breast milk (43).

    After you give birth, your melatonin levels are highest at night. Because of this, breastfeeding in the evening may contribute to the development of your baby’s circadian rhythms (44).

    Although melatonin is a natural component of breast milk, no data exist on the safety of melatonin supplementation during breastfeeding. For this reason, using melatonin supplements while nursing is not recommended (1, 44).

    Summary

    Although babies start producing melatonin after birth, their levels are initially low and can be naturally supplemented by breast milk. There’s insufficient evidence to recommend using melatonin supplements if you’re nursing.

    Melatonin and children

    Healthy children and adolescents may have trouble falling asleep too.

    The prevalence of sleep disorders is particularly high in children with developmental disorders such as autism spectrum disorder (ASD) and attention deficit hyperactivity disorder (ADHD) (45).

    The effectiveness of melatonin in children and adolescents is still being investigated.

    One review of seven studies of melatonin use in children and adolescents found that children receiving melatonin as a short-term treatment fell asleep faster and slept longer than children receiving a placebo (46).

    A small study followed up on people who had been using melatonin since childhood, for about 11 years. It found that their sleep quality wasn’t notably different from that of a control group who hadn’t used melatonin. This suggests their sleep problems normalized over time (47).

    Studies on melatonin for children with developmental disorders such as ASD and ADHD show mixed results. Generally, they’ve found that melatonin may help children with such conditions sleep longer, fall asleep faster, and have better sleep quality (48, 49).

    Tolerance, dosage, and precautions

    Melatonin is well tolerated in children. Although there’s some concern that long-term use may delay puberty — because a natural decline in evening melatonin levels is associated with the onset of puberty — more studies are needed (50).

    Melatonin supplements for children are often sold in the form of gummies.

    Dosage varies by age, and more research is needed to determine the optimal dosage and effectiveness. Nonetheless, common recommendations are 1 mg for infants, 2.5–3 mg for older children, and 5 mg for young adults (45).

    Additionally, because researchers don’t yet understand the long-term effects of melatonin use in children, it may be best to help your kids implement good sleep practices — if those are not already in place — before you give them melatonin (43, 45, 51).

    Summary

    Melatonin may improve sleep onset in children, as well as various aspects of sleep quality in children with developmental disorders. However, the long-term effects of melatonin treatment in children remain largely unknown.

    Melatonin and older adults

    Melatonin secretion decreases as you age. These natural declines may lead to poor sleep in older adults (52).

    Although research is ongoing, studies suggest that melatonin supplements may improve sleep onset and duration in older adults (53, 54).

    Melatonin may also help people with mild cognitive impairment or Alzheimer’s disease. Some studies suggest that melatonin improves sleep quality and morning alertness in individuals diagnosed with these conditions. Still, more research is needed (15, 16).

    While generally well tolerated, melatonin supplements may increase daytime drowsiness in older adults, especially when combined with prescription sleep medications (55).

    Notably, research shows that the anti-inflammatory effects of melatonin may benefit older adults, who tend to have more chronic inflammatory conditions, such as heart disease, than younger adults (56).

    The most effective dose of melatonin for older adults is 1–6 mg, but it’s best to try the lowest possible dose first. Caution is warranted because melatonin can interact with common prescription drugs (54, 57).

    Older adults should be sure to talk with a pharmacist or doctor before taking melatonin.

    Summary

    Melatonin levels naturally decrease as you get older. Supplementing with low doses may help improve sleep quality in older adults.

    The bottom line

    Melatonin is an effective supplement that may help you fall asleep, especially if you have insomnia or jet lag. It may offer other health benefits as well.

    If you’re considering melatonin, it’s important to talk with a doctor or pharmacist first to find out whether it’s right for you and whether it could interact with any medications you’re taking.

    Then, you can start with a low dose of 0.5–1 mg 30 minutes before bed. If that doesn’t help, try increasing your dose to 3–5 mg.

    Melatonin is generally well tolerated, although mild side effects are possible.

    Just one thing

    Try this today: If you already practice healthy sleep habits but find that they’re not enough, melatonin is a relatively cheap, safe, and effective option to promote good sleep for most people.

    Food fix: Foods for better sleep

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