Melatonin is a hormone produced by all mammals that plays a significant role in the regulation of sleep and circadian rhythms. Dubbed the “sleep hormone,” melatonin is formed in the brain’s pineal gland in response to falling light levels to prepare the body for sleep.
In recent years, synthetic melatonin supplements marketed to treat a variety of sleep disorders have become ubiquitous. From 2007 to 2012, melatonin use in the U.S. doubled and it now ranks as one of the nation’s most popular supplements. Its popularity stems in part from its image as a natural alternative to traditional sleep medications, which are known for side effects.
Although melatonin supplements are considered “natural,” this does not necessarily mean they are harmless. Categorized as a dietary supplement by the Food and Drug Administration, melatonin regulation is loose in the U.S. and does not require the extensive research that prescription and over-the-counter sleep aids must undergo to earn access to consumers.
While those struggling to sleep may be desperate to do as much as possible to get shut-eye, more is not always better. It is important to be aware of the safety risks posed by taking too much melatonin.
Melatonin is available to purchase in any quantity, without a prescription in the U.S. However, there is currently no formal consensus on the optimal dosing regimen for this supplement. Studies frequently use doses ranging from 0.1 to 10 milligrams, but 2 to 3 milligrams is often considered an appropriate amount to start.
There are many challenges to determining the appropriate amount of melatonin for any one person to take. Individual responses to this supplement can vary considerably due to factors that are not fully understood but can include age, gender, specific sleep issues, other health conditions, and timing of administration.
In addition, not all melatonin supplements are created equal. Differences in preparation can significantly alter melatonin’s impact. Depending on the formulation, taking 1 to 10 milligrams of melatonin can raise the body’s melatonin blood levels anywhere from 3 to 60 times the normal amount.
Melatonin users should also be wary of the dosages listed on supplement labels, which have shown to be alarmingly inaccurate. A random sampling of 31 brands of melatonin supplements determined that most did not contain the labeled dose, with the actual amount ranging anywhere from less than 80% to nearly 500% as much. Additionally, over one quarter of the supplements contained serotonin. Consumers should look for products labeled United States Pharmacopeial Convention Verified for the most reliable formulation.
Despite the lack of data and variability around dosing regimens, with typical use, melatonin is largely considered safe and is generally well-tolerated in healthy adults. The risk of side effects is low, but can include mild headache, dizziness, nausea, and sleepiness.
So far, there is no clinical evidence that short-term melatonin use can cause long-term problems in healthy adults. It is important to note, however, that high-quality studies addressing this topic are lacking. The current body of evidence consists mostly of small studies and case reports.
In one study, 12 adult males were administered intravenous melatonin in doses of 10 milligrams, 100 milligrams, or a placebo. There were no reported differences in sedation among the groups, and there were no harmful reactions. A second study gave five patients 1,000 milligrams of oral melatonin for approximately four weeks. While changes in pituitary hormones were observed, no toxic effects were reported.
Between 2000 and 2001, three case reports documented people who were admitted to emergency rooms for suicide attempts involving melatonin, each taking between 60 to 150 milligrams. Two of the individuals also took pharmaceutical drugs and alcohol with the melatonin. Minimal side effects were reported, and each person was discharged without issue after receiving appropriate care.
It is important to note that just because a supplement is unlikely to be lethal, that does not mean that unwanted or troubling side effects cannot occur. Concerning symptoms have been reported with higher doses of melatonin.
Possible symptoms of too much melatonin include:
Because melatonin can affect the cardiovascular, dermatologic, and central nervous systems, those with other conditions may be vulnerable to additional risks. Evidence suggests that melatonin supplementation may induce depression, particularly in people predisposed to or currently experiencing this malady. Research on this topic, however, is conflicting, since some studies have demonstrated the potential for melatonin to treat depression.
People taking blood thinners, like warfarin, and benzodiazepines should be careful, as there is a possibility for interaction. Those with epilepsy should also exercise caution, as melatonin has been associated with increased seizures.
Research suggests that elderly people, who have lower natural levels of melatonin, may be more sensitive to the effects of melatonin supplements. Therefore, older people are encouraged to check with their doctor before taking melatonin and start with the lowest possible dose.
Compared with most other sleep aids, melatonin clears the body quickly, and its effects are short-lasting. If you are experiencing unwanted symptoms after taking melatonin, you can most likely just wait it out as your body processes the drug. However, when in doubt, it’s always a good idea to seek professional advice. Don’t hesitate to contact your doctor or local poison control for guidance on managing worrisome symptoms or determining whether you need medical care.
Minimal research exists on using melatonin beyond a few months. Therefore, there is much we don’t know about its long-term effects. There is not even agreement on what constitutes long-term melatonin use.
Most of the concern around taking melatonin for extended periods centers around it’s potential to affect reproductive hormones. While the exact mechanism of action is still unclear, some reports indicate that melatonin may inhibit reproductive hormones.
Nearly 25% of children have difficulty sleeping, and parents increasingly turn to melatonin for help. Between 2007 and 2012, pediatric melatonin use rose seven-fold and is now the second most common natural supplement in this age group. However, further research is needed regarding the safety of melatonin for children.
There are reasons for parents to be cautious about the patchy data on melatonin in kids. It appears that children may be particularly vulnerable to the possible effects of this supplement on reproductive hormones. Melatonin has been associated with puberty delays, irregular menstruation, and overproduction of the hormone prolactin. It is important to note, however, that research on this topic is conflicting, and experts agree that the topic is understudied.
Parents should also be aware that melatonin may decrease blood pressure or serum glucose levels. Children taking other medications or who have illnesses affecting these systems should consult their doctor before starting melatonin.
Melatonin should only be used for children under the guidance of a doctor. Most pediatric sleep disorders can be managed with behavioral changes, such as proper sleep hygiene and cognitive therapy. Melatonin should not be used before trying other measures.
While melatonin is largely viewed as safe, it is not without risk. Perhaps the most significant risk is what we don’t know about this supplement. While you’re unlikely to cause any serious damage using melatonin, it’s best to proceed with caution. Seeing a doctor for an accurate diagnosis of a sleep condition and determining whether melatonin is suitable for your situation can save you precious time and energy.