That can be a problem because sleep is essential to good health. Research shows that poor sleep is associated with an increased risk of obesity, Type 2 diabetes, hypertension, cardiovascular disease and several other health conditions.
If you are having trouble sleeping, studies suggest that some over-the-counter supplements, including melatonin and magnesium, may help. However, there are important limitations. Neither acts as a sedative or treats sleep disorders like chronic insomnia, defined as difficulty falling or staying asleep at least three times a week for three months or more.
Unlike prescription medicines, dietary supplements are not reviewed by the Food and Drug Administration in the same way.
Melatonin: When falling asleep is the problem
Melatonin supplements can help align your body’s internal clock with the natural light-dark cycle, making it easier to achieve your preferred sleep schedule, said Anita Shelgikar, immediate past president of the American Academy of Sleep Medicine and professor of neurology at the University of Michigan Medical School.
Melatonin works by mimicking the hormone naturally produced by the pineal gland in the brain, which regulates the sleep-wake cycle. In response to darkness, the brain releases melatonin to promote sleepiness. As morning approaches, melatonin levels gradually decline, helping the body wake up.
A 2024 review of 26 randomised controlled trials found that melatonin reduced the time taken to fall asleep and increased total sleep duration. The strongest results were seen with a daily dose of 4mg, taken about three hours before the desired bedtime.
For most healthy adults, taking a low dose of between 1mg and 3mg daily for a few weeks is generally considered safe. In most cases, however, doses above 5mg are not recommended because there is no reliable evidence that higher amounts provide greater benefit, said Michael Grandner, director of the Sleep and Health Research Programme at the University of Arizona.
Grandner also advises starting with the lowest effective dose because supplements are often more potent than the labelled strength when first manufactured before gradually degrading over time. He also prefers quick-dissolve formulations where possible, noting that gummies can make it difficult to know exactly how much melatonin is being absorbed and when.
Melatonin is generally best taken two to three hours before your intended bedtime. Shelgikar also recommends maintaining a consistent bedtime and wake-up time, exposing yourself to bright light in the morning and reducing light exposure for about an hour before bed.
If this approach is not effective, consult a healthcare professional for a personalised treatment plan. Taking melatonin at the same time your brain is already producing sufficient amounts is unlikely to provide any additional benefit because, as Shelgikar explained, your “melatonin receptors are full”.
According to Pieter Cohen, an internist at Cambridge Health Alliance and associate professor at Harvard Medical School, accidental overdoses in children have resulted in hospitalisations.
The American Academy of Sleep Medicine also recommends against using melatonin to treat chronic insomnia in adults. Grandner said the likelihood that any nutritional supplement will successfully treat insomnia is very low.
Older adults and medication considerations
The body’s natural production of melatonin during the night gradually declines with age. Certain medicines commonly prescribed to older adults, particularly beta blockers, can further suppress melatonin production, Grandner said.
In these situations, a low-dose melatonin supplement, generally less than 5mg, may help replace some of the hormone that the body is no longer producing naturally.
However, melatonin can interact with certain medications, including bloodthinners. Experts recommend obtaining magnesium through the diet by eating foods such as green leafy vegetables, legumes, nuts, seeds and whole grains rather than relying on supplements.
Even so, Grandner said he has “no hesitation in recommending it for people who have more mild or transient issues, or if they want to boost what they’re already doing. It’s likely not harmful, and it’s likely at least a little bit helpful, but just don’t expect more from it than it can deliver.”
Researchers have proposed two possible reasons why magnesium may support better sleep. Firstly, it plays a role in the body’s production of melatonin. To make melatonin, the body converts the amino acid tryptophan into serotonin, and magnesium helps support an enzyme involved in converting serotonin into melatonin, Grandner explained.
Secondly, magnesium helps maintain normal nerve and muscle function and may promote muscle relaxation, although the evidence for relieving muscle cramps remains mixed.
Research examining magnesium supplementation for sleep has generally involved small studies or shown only modest benefits. One small trial published in 2025 found that participants who took 250mg of magnesium bisglycinate daily for one-month experienced better sleep than those given a placebo.
“The effects generally are not as large as people tend to think they are, but they’re not nothing either,” said Grandner, who was not involved in the study.
Choosing the right supplement
For those wishing to try magnesium, Shelgikar recommends taking 250mg of magnesium glycinate each day as part of a bedtime routine. She emphasised, however, that this advice is based largely on anecdotal evidence because research on magnesium and sleep remains limited. Anyone who continues to experience sleep problems after several weeks should consult a doctor.
Cohen also advises avoiding magnesium citrate if your aim is to improve sleep because it is commonly used as a laxative, “and that’s certainly not something you want to take at night”.
It is also worth remembering that magnesium supplements may cause gastrointestinal side effects, including diarrhoea, vomiting and abdominal cramps. Magnesium can interact with several prescription medicines, including certain antibiotics, blood pressure drugs and medications used to treat bone loss. According to Shelgikar, it may also worsen some medical conditions, including the neuromuscular disorder myasthenia gravis.
Ultimately, while both melatonin and magnesium may help some people with certain sleep difficulties, neither should be viewed as a cure for persistent sleep disorders. Anyone with sleep problems should seek medical advice to identify the underlying cause and determine the most appropriate treatment.
