Melatonin Research Analysis

Q: Is melatonin found in food?

Melatonin is also found in a variety of foods, although typically in small amounts.[25] Sources of melatonin that are commonly consumed include:[26][27] Tomatoes:3–114 nanograms per gram (ng/g)[28][29] Walnuts: 3–4 ng/g[30] Cereal (barley, rye): 300–1,000 picograms per gram (pg/g)[25] Strawberries: 1–11 ng/g[28] Night-time milk (functional food product): 10–40 nanograms per milliliter (ng/ml)[31] Wine (from grapes): 50–230 picograms per milliliter (pg/ml)[28][32] Beer (from hops): 52–170 pg/ml[33] Cherries: 2.06–13.46 ng/g[34]

Q: Can melatonin help with jet lag or shift work?

Yes. The current evidence suggests that melatonin can ease sleep problems associated with jet lag. In situations where external stimuli (sunlight and darkness cycles) and internal stimuli (the internal clock) are not in sync, supplemental melatonin is thought to help re-establish this synchronization. A Cochrane meta-analysis of 10 studies which examined jet lag due to flights traversing five or more time zones found that melatonin taken at the destination bedtime was significantly more effective than placebo at normalizing circadian rhythm and reducing symptoms of jet lag. One of these studies found that doses of 500 mcg (0.5 mg) and 5 mg were similarly effective at reducing jet lag, but participants reported falling asleep faster with the 5 mg dose. The two studies in the meta-analysis reporting individual statistics found that about 17% of participants still experienced severe jet lag after taking melatonin, compared to 67% after taking a placebo.[23] Overall, melatonin seems to be helpful to re-establish a healthy circadian rhythm after experiencing jet lag. Interestingly, melatonin could also be used to treat social jet lag (when changes in sleep habits over the weekend disrupt sleep the following week).[24] Future studies may shed more light on this.

Q: Can a combination of melatonin and cannabidiol (CBD) help with sleep?

There is currently no compelling evidence that a combination of melatonin and cannabidiol (CBD) improves sleep beyond what can be explained by melatonin alone. Melatonin and CBD is a popular supplement combo for improving sleep, based on supposedly complementary mechanisms of action (i.e., melatonin promoting sleep onset and CBD theoretically reducing sleep disruption). However, there is little evidence that CBD can improve sleep quality on its own.[35] But what about when combined with melatonin? One 4-week randomized controlled trial examined the effect of melatonin and several cannabinoids (including CBD), alone or in combination, on sleep in 1,784 people with sleep disturbances.[36] Ultimately, taking a combination of CBD, cannabinol (CBN), and melatonin did not clearly reduce sleep disturbances compared to taking melatonin alone. Unfortunately, the lack of placebo group and the inclusion of other cannabinoids (e.g., CBN) limits the generalizability of this study. It’s possible that taking CBD could increase melatonin levels by inhibiting the enzyme CYP1A2,[37] which metabolizes melatonin.[38] In theory, this could mean CBD would make melatonin supplements more potent. However, this has not yet been directly confirmed in humans.

Q: Can melatonin affect dreams?

Melatonin supplementation might impact dreams, but it’s hard to say much with certainty. Theoretically, melatonin could promote dreaming by increasing time spent in REM, a primary sleep stage when dreaming occurs. One randomized controlled trial of 22 young adults did find that taking melatonin before bed increased how bizarre participants rated their dreams.[10] However, aside from this small study, there isn’t much research confirming a dream-enhancing or dream-altering effect of melatonin. In two randomized controlled trials of people with sleep disorders, melatonin supplementation increased time spent in REM but had no obvious effect on the number, intensity, or quality of dreams.[11] And another study of 30 people with Parkinson’s disease found melatonin supplementation had no apparent effect on the frequency of vivid dreams compared to placebo.[12] In some studies, people have stopped taking melatonin due to nightmares, although this is a rare occurrence.[13][14] It’s also not clear whether the nightmares were caused by melatonin or just happened to occur while the person was taking melatonin. Furthermore, one randomized controlled trial reported no increase in the rates of nightmares with melatonin supplementation.[15]

Q: Will supplementing melatonin affect my own production of melatonin?

Supplementing melatonin doesn’t appear to affect the body’s own production in a negative way. Studies that have administered melatonin at doses of 0.5 mg,[16] 5.0 mg,[17] and 50 mg[16] have found no significant effect on the body's ability to produce a basal level of melatonin. One trial even found that people with insomnia who took 2 mg of melatonin nightly for 6 months had higher natural melatonin synthesis after cessation of the supplement than a historical sample of participants with insomnia who didn't take melatonin.[18]

Q: Is melatonin supplementation safe?

In an umbrella review of melatonin supplementation, reported adverse effects appeared uncommon, and were predominantly mild effects such as dizziness, nausea, headaches, and fatigue.[19] In some studies, doses as high as 75 mg have been used without any serious adverse effects reported.[20] It’s worth noting that there are some concerns regarding the safety of melatonin in young children and infants. In a report by the CDC, melatonin ingestion by children resulted in a number of hospitalizations between 2012 and 2021, including at least two infants who ultimately died.[21] ⚠️ Caution: Melatonin supplement safety There are two important things to keep in mind when it comes to the safety of melatonin supplementation: First, one study found that many melatonin supplements often do not contain the amount of melatonin claimed on the label (sometimes containing substantially more), and second, some of the supplements that were tested in this study were contaminated with serotonin, a neurotransmitter with unclear safety when ingested orally.[22]

Morgan Pfiffner

Melatonin

•Last Updated: November 2, 2023

Melatonin is a hormone secreted in the brain that regulates sleep. It appears to be highly sensitive to light therapy and dark therapy. Oral ingestion of melatonin may be used as a sleep aid. It is non-addictive.

Dosage

Examine Database

Research feed

Melatonin is most often used for

Morgan Pfiffner, MS

Natalka Roshak, AB

•

Peter Woznik, ND, MSc

Last Updated:November 2, 2023

Dosage Information
Examine Database
Research feed
Frequently asked questions
Update History
References

What is melatonin?

Melatonin is a neurohormone, secreted by the pineal gland in the brain, that regulates the sleep/wake cycle. Light suppresses melatonin synthesis. The primary use of melatonin as a supplement is to normalize abnormal sleep patterns.

Is melatonin found in food?

What are melatonin’s main benefits?

Irregular sleep patterns are associated with a wide variety of health problems. Melatonin is the hormone used by your body to help you fall asleep, and thus supplementation is seen as a way to help get regular sleep. This is particularly useful for people who engage in shift work or are jet lagged.

Melatonin may also ease symptoms of irritable bowel syndrome (IBS),^[3] reduce tinnitus severity,^[4] lower blood sugar levels in people with type 2 diabetes,^[5] and result in small (perhaps negligible) amounts of weight loss.^[6] There is ongoing research into melatonin supplementation as an adjunct treatment in cancer,^[7] although human studies on the topic are limited.

Some demographics tend to have irregular melatonin production or metabolism in their body. Smokers may be less responsive to supplementation due to increased enzymatic breakdown of the molecule, and older people seem to produce less melatonin during night time. This may be why melatonin seems to have a more consistent effect in older people.^[8]

Finally, one meta-analysis suggests that melatonin supplementation may modestly improve symptoms of depression, although studies on the topic vary widely in their conclusions. While melatonin is likely safe and potentially useful for depression, it isn’t clear that it will work in all cases.^[9]

Can melatonin help with jet lag or shift work?

Can a combination of melatonin and cannabidiol (CBD) help with sleep?

What are melatonin’s main drawbacks?

In typical dosages, melatonin appears fairly safe. Side effects are both uncommon and usually mild, including daytime sleepiness, headache, and nausea. Very rarely, serious adverse effects resulting from melatonin supplementation (often in very high doses) have been reported. Melatonin is not addictive.

Can melatonin affect dreams?

Will supplementing melatonin affect my own production of melatonin?

Is melatonin supplementation safe?

Can melatonin supplementation reduce testosterone levels in men?

How does melatonin work?

As a hormone, melatonin’s main function is to promote the onset and maintenance of sleep. It achieves this by activating melatonin receptors in the brain, which inhibit neuronal activity and regulate the body’s circadian rhythm. Melatonin receptors have been identified in many other tissues as well (including the intestinal tract, pancreas, and immune cells), which may explain some of melatonin’s other health effects.

What are other names for Melatonin?

Note that Melatonin is also known as:

N-Acetyl-5-Methoxytryptamine
Melatonine
Melovine
Melatol
Melatonex
Circadin

Dosage information

For regulating the sleep cycle and improving sleep disorders, doses of melatonin between 300 micrograms (μg) and 5 mg have been shown to work.^[1]^[2] Start with 300 μg, and work up to 5 mg as needed. The benefits of melatonin are not dose-dependent — taking more will not help you fall asleep faster. That said, the most effective dose is an area of ongoing research.

To help with sleep, take roughly 30 minutes before going to bed, although some people may benefit from taking melatonin as much as 3 hours earlier.

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