Melatonin supplements are currently widely available in the United States without a prescription and in many delivery forms: capsules, tablets, fast-dissolve tablets, gummies, and liquids. Marketed in the United States to both adults and children as a safe and natural sleep aid, melatonin supplements and the mechanism by which they induce drowsiness in humans do not yet seem to be fully understood by general consumers. Additionally, more long-term studies of melatonin’s effects are needed, particularly in the area of pediatrics.
Michael Grandner, PhD, MTR, CBSM, FAASM, assistant professor of psychiatry and director, Sleep and Health Research Program, College of Medicine, University of Arizona, calls melatonin supplements “quite safe, especially compared with sleeping medications.” However, the United States “may be the only developed country in which melatonin is sold as a supplement without a prescription,” he adds.
Melatonin-supplement users will want to weigh their pros and cons and make sure they don’t fall for three common misconceptions regarding melatonin supplements.
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Misconception #1: Melatonin Is a Sleeping Pill
“It’s actually more complicated than that,” Grandner says. “Melatonin is way more than a chemical that tells the body to sleep. It’s a chemical that tells our bodies it’s nighttime, and nighttime is the time that we try to sleep. Melatonin is not a sleep inducer; it’s a signal to the body of where the clock is.”
Grandner explains further that the body’s natural melatonin-secretion process works something like this: The brain, which knows nighttime is here thanks to its internal clock working in tandem with signals from the environment (such as lack of sunlight), directs the pineal gland to secrete melatonin. This hormone then travels around the body binding to melatonin receptors within all the different cell systems, alerting these systems that nighttime has arrived. Melatonin essentially “puts all cells, tissues, and systems into ‘night mode’ and keeps them all on the same page,” Grandner says. Night mode triggers different actions in various body systems; for instance, it may stimulate the liver to start making cholesterol. It also triggers drowsiness.
Supplementing with additional melatonin, Grandner explains, “nudges the hands on your internal clock a little bit.” Taking melatonin as early as an hour or two before bed, when one’s natural melatonin levels are low but rising, will shift that clock forward somewhat and induce drowsiness sooner than normal.
Likewise, taking melatonin “first thing in the morning, as your levels are dropping, can extend your biological night a little bit,” Grandner says.
A sleeping pill, on the other hand, “has very little to do with the clock,” he states.
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Misconception #2: The More Melatonin a Person Takes, the Better It Works
No dose-response effect exists for melatonin supplements, Grandner says. “It doesn’t necessarily work better the more you take. If anything, the opposite is true.”
Grandner explains that the standard supplemental-melatonin dose for “the vast majority of adults” is 0.5 mg up to about 3 mg. “But if you take two tablets, you are not going to have double the effect,” he states, and he adds that a lower dose often works better. “You’re trying to nudge the internal clock, not overpower it,” he says.
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Misconception #3: Melatonin Is Natural and Therefore Guaranteed Safe for All
Some might think that because melatonin is a natural hormone secreted by our own bodies, melatonin supplementation carries absolutely no risk and is 100% safe. It is true that melatonin supplements are quite safe for most adults and less risky than pharmaceutical sleep-inducing drugs; however, there can be some negative effects. For instance, Grandner says, side effects can include headaches or dizziness and unpleasant stomach symptoms. For some adults, melatonin supplements can cause sufficient drowsiness as to make driving unsafe, and they can potentially negatively affect mood.
Additionally, “melatonin does other things in the human body beyond telling the body’s systems that nighttime has arrived,” Grandner explains. “For example, there is a lot of melatonin in the digestive system that has nothing to do with signaling nighttime, and there is melatonin within the cardiovascular system that is not necessarily related to nighttime signaling, either.” For this reason, taking supplemental melatonin may present some risk. Grandner also describes how, when provided with supplemental melatonin over the long term (several months), the human body may lower its own melatonin production.
One area of controversy for which a significant dearth of knowledge exists is pediatric melatonin supplementation. Katherine M. Sharkey, MD, PhD, FAASM, assistant professor, Alpert Medical School of Brown University (Providence, RI), says that most of the studies of melatonin supplementation in pediatric populations have been in small samples of children with neurologic disabilities or psychiatric disorders, and in those populations, melatonin supplements do appear to help improve sleep duration and latency to sleep onset in children with “very irregular, disrupted sleep-wake patterns.” However, very little data exists on giving melatonin to otherwise healthy children with insomnia, Sharkey explains. She adds that melatonin is known to affect growth hormone and play a role in pubertal onset. “Disorders of the hypothalamic-pituitary-gonadal axis, such as delayed puberty, precocious puberty, and amenorrhea, have been associated with abnormal plasma melatonin secretion patterns,” she says, and cites a review article by David Kennaway published last year in the Journal of Paediatrics and Child Health.(1) In the pediatric population, much more research on melatonin supplementation is needed.
1. Kennaway DJ, “Potential safety issues in the use of the hormone melatonin in paediatrics,” Journal of Paediatrics and Child Health, vol. 51, no. 6 (June 2015): 584-589
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