In a world where the pursuit of restorative sleep is increasingly paramount, melatonin supplements have emerged as a popular and cost-effective over-the-counter alternative to sedative-hypnotics. Available in various forms such as tablets and gummies, melatonin has seen a meteoric rise in usage among both adults and children, with the national melatonin market witnessing a staggering 150% increase in sales between 2016 and 2020. However, the supplement industry’s inherent challenges, including a lacking Food and Drug Administration (FDA) oversight, have left consumers vulnerable to potential discrepancies in product labeling and safety, as illustrated by a recent study investigating the discrepancy in melatonin content versus labeled dosage in melatonin supplements. But it is not only the accuracy of supplement labels that is being scrutinized but also the fundamental question of whether melatonin truly delivers on its promise of improved sleep quality.
Melatonin and Sleep
Melatonin, a hormone synthesized by the brain’s pineal gland, is often dubbed the “sleep hormone” due to its pivotal function in controlling our sleep-wake cycle. As evening sets in, melatonin concentrations within the body naturally rise, fostering the onset of sleep. In contrast, daytime sees a decline in melatonin levels, contributing to our ability to maintain alertness and wakefulness. For individuals grappling with certain sleep-related issues, melatonin supplements have emerged as a popular remedy for restoring the sleep-wake cycle.
While melatonin has demonstrated potential as a sleep aid, it’s essential to consider the caveats related to its use, which I’ve discussed with sleep expert Dr. Matthew Walker on The Drive and in a more recent “Ask Me Anything” episode. Though melatonin is generally deemed safe across a range of doses, there is insufficient evidence to confirm the safety of long-term supplementation in adults, and especially in children, which is how it’s typically consumed in cases of persistent sleep disturbances. It’s possible that consuming high doses – commonly found in supplements – over extended periods could disrupt the body’s natural melatonin production and/or sensitivity to the hormone. Additionally, melatonin may cause side effects such as headaches, nausea, and drowsiness and interact with certain medications, with the risk rising in tandem with dosage increases.
The risks associated with high doses make sense when we consider how comparatively little melatonin the body produces naturally. The pineal gland releases less than 0.1 mg of melatonin at night, and supplementation with just 0.1-0.3 mg is sufficient to elevate plasma concentrations to these normal physiological levels in healthy adults. Most over-the-counter melatonin supplements significantly exceed this amount, with nominal doses typically ranging from 1-20 mg, raising the risk of undesirable side effects or long-term effects on natural melatonin signaling. To avoid these effects, I therefore recommend patients not take more than about 0.3 mg nightly – if they must take it nightly – and if possible, to use only as an occasional intervention instead.
But adhering to these guidelines depends critically on our ability to trust the amounts listed on the product label. Unfortunately, melatonin supplements are not regulated by the FDA in the same way prescription drugs are, and this regulatory gap turns the actual melatonin content in supplements into something of a guessing game, with implications for lifestyle and clinical use.
About the Study
In a 2023 study published by the Journal of the American Medical Association, Cohen et al. investigated the presence and quantity of melatonin, cannabidiol (CBD), and serotonin in 25 over-the-counter sleep aid gummies with nominal melatonin content ranging from 1-10 mg. The researchers screened for serotonin due to its history of appearing as a contaminant in melatonin products.
Their findings revealed that one product contained 31.3 mg of CBD without detectable levels of melatonin, despite “melatonin” appearing on the label. In the other 24 products, melatonin levels varied significantly, ranging from 1.3 to 13.1 mg per serving. Notably, the actual melatonin content deviated considerably from the labeled amounts, with discrepancies up to a striking 347%. A mere three of the 25 products (12%) had melatonin quantities within ±10% of the declared amount, suggesting that a vast majority (22, or 88%) of these sleep aids were inaccurately labeled, potentially leading to unintended consequences for consumers. In all but two of these 22 products, the direction of the deviation was positive, meaning that they contained more – not less – melatonin than the label indicated.
Regarding CBD content, five products listed CBD as an ingredient, with actual quantities ranging from 104% to 118% of the labeled amounts. Importantly, no serotonin was detected in any of the products.
The consequences of these inaccuracies in labeling are worrisome, given the small dose required to raise plasma concentrations to nighttime levels. As a result, adhering to the instructions on melatonin gummy labels could lead individuals to consume 40-130x higher amounts of melatonin than intended.
When and how should melatonin be used?
Even before seeing results from this study, I generally have not endorsed the use of exogenous melatonin apart from a few specific circumstances, and even then, only at very low doses (ideally between 0.3-0.75 mg). While melatonin is recognized for its role in regulating sleep timing, it’s important to note that it does not directly impact the duration of sleep, and we do not have clear evidence that it affects sleep quality under normal circumstances.
However, one of the less “normal” circumstances in which melatonin supplements can be beneficial is in traveling across multiple time zones. Melatonin can effectively alleviate the symptoms of jet lag, a condition often resulting in disrupted sleep, daytime fatigue, and impaired cognitive function. To harness the benefits of melatonin in counteracting jet lag, it is recommended to take the supplement 45 minutes to an hour prior to bedtime, which enables the body to recalibrate its sleep rhythm and adapt to the new time zone more efficiently.
Moreover, as individuals age, their circadian rhythms, which regulate sleep and other physiological processes, tend to change, leading to disrupted sleep patterns and overall sleep quality. This is characterized by a shift towards a “morning” chronotype and reduced rhythmicity in hormone release. Sleep in older adults tends to be shorter, more fragmented, and often shifts earlier. In contrast, delayed sleep-wake phase disorder (DSWPD) affects individuals who struggle to fall asleep. In both of these cases, melatonin supplementation may help restore the desired sleep-wake cycle.
Melatonin may also mitigate the negative impact of artificial blue light on sleep patterns. Electronic devices, such as smartphones and tablets, emit blue light, which can suppress melatonin production and disrupt sleep. Studies have shown that a mere two-hour exposure to blue light in the evening can inhibit melatonin release, with the strongest suppression occurring at shorter wavelengths. Of course, the best way to avoid this negative impact of blue light is to limit screen exposure close to bedtime, but when such exposure is unavoidable, melatonin supplementation may help to counteract the harmful effects on sleep.
Melatonin supplementation can serve specific functions described above, but aside from these, there is a lack of substantial evidence supporting its clinical benefits. Even in the particular cases that may merit melatonin use, I never recommend doses exceeding 1 mg – doses which are sufficient to elevate plasma concentrations to these normal nighttime levels but below the doses of most over-the-counter melatonin products.
Most over-the-counter melatonin supplements contain anywhere from 1-20 mg – at least an order of magnitude more than is produced in the body. With research showing that these products may in actuality contain up to 347% of the indicated melatonin dose, melatonin supplementation may ultimately be an unsuitable long-term solution for improving sleep quality. Instead, focusing on natural methods to boost melatonin production, such as reducing light exposure in the hours before sleep, could be a more effective and sustainable approach.
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