Sleep has become the new health and wellness frontier in a world ravaged by a sleep deprivation “epidemic’ — especially so, due to the increased health consciousness among people in the post-pandemic world. It’s this pursuit of a good night’s sleep that has introduced the world to melatonin supplements — in the form of fruity gummies, easy-to-consume pills, and water-soluble flavored powders. Melatonin’s rise to fame as a widely-used over-the-counter remedy for sleep issues is driven by its reputation as the hormone regulating the body’s sleep-wake cycle; it’s produced naturally in the pineal gland of the brain in response to darkness. The popularity of melatonin, however, is beginning to be tarnished by anecdotal accounts of the haunting side-effects it can allegedly induce.

Many claim that consuming melatonin supplements have led them to experience vivid nightmares. The question that’s keeping people up, then, is whether there is in fact a causal relationship between the two.

The reason people are drawn to melatonin supplements is two-fold: first, it reduces the time one takes to fall asleep by four to eight minutes; second, it can one’s increase overall sleep duration. The nightmares reported by a subset of melatonin users might be a result of the latter. When melatonin increases one’s cumulative sleep duration, it also extends the amount of time spent in the REM (rapid-eye movement) stage of sleep. Incidentally, this is the phase where most of the dreaming occurs. Some experts therefore believe that, since melatonin extends this phase of sleep, it may seem like it is inducing nightmares when it’s merely allowing more time for people to dream. Melatonin, by itself, isn’t known to have any effect onwhether these dreams turn out to good or bad.

Moreover, lack of sleep is often a consequence of psychological distress. While popping a melatonin gummy before bedtime may help one fall asleep faster and stay asleep longer, it doesn’t undo the distress that lies behind the sleeplessness. Unfortunatey, these same psychological stressors can induce nightmares, too. And since melatonin extends the phase of sleep where we dream, it can seem like the culprit when, actually, it isn’t. Interestingly, melatonin is believed to relieve anxiety and stress; but, apparently, not enough to keep nightmares at bay.

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Largely, then, it appears that the link between melatonin and nightmares is less causal and more circumstantial. A part of it might also be influenced by our confirmation biases and the nocebo effect, which tricks the body into thinking that it’s experiencing negative effects from medicines, simply because one was expecting the negative effects.

Nonetheless, while melatonin supplements are generally considered safe for short-term use in appropriate doses (ideally, between 0.1 mg and 5 mg), their long-term effects remain a subject of ongoing research. So, although there is limited empirical evidence to support a causal relationship between melatonin supplements and nightmares, it also cannot be definitively said that melatonin doesn’t make dreams worse.

Moreover, because it’s a wellness supplement, many products containing melatonin aren’t too well regulated either, which means that the dosage they contain could be much higher than than what they advertise. “[M]elatonin content in these unregulated, commercially available melatonin supplements ranged from — 83% to +478% of the labeled content,” said Rebecca Robbins, an instructor in the division of sleep medicine for Harvard Medical School. “There is a view that if it’s natural, then it can’t hurt… The truth is, we just really don’t know the implications of melatonin in the longer term, for adults or kids.”

So, the problem may be these higher doses as nightmares are a recorded (but not understood) side effect of consuming “too much” melatonin, reportedly. To make matters worse, some experts note that the dosage that’s being marketed is also unreasonably high.

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“There are melatonin receptors all over the brain in regions like the cortex, thalamus, substantia nigra, nucleus accumbens, amygdala, hippocampus, cerebellum, and your eyes. These are areas that are heavily involved in learning, memory, processing fearful events and threatening stimuli, stress relations, and cognitive executive function. So, when taking an amount of melatonin that is larger than what the body is used to, it is not surprising why these areas are overactive with the amount of melatonin that is available on the market,” explains Zeke Medina, an adult sleep coach.

Further, it’s also possible that the melatonin supplements available in the market buy are mixed with other chemicals. As Robbins notes, “We cannot be certain of the purity of melatonin that is available over the counter.”

However, the popularity of the supplements is growing, undeterred by accounts of the spooky side effects. In fact, calling melatonin the next Vitamin D in the universe of health and wellness supplements, a study from March this year states: “[T]here may be similarities between the widespread concern about Vitamin D deficiency as a ‘sunlight deficiency’ and reduced melatonin secretion as a result of ‘darkness deficiency’ from overexposure to artificial blue light… Both act as hormones, affect multiple systems through their immune-modulating, anti-inflammatory functions, are found in the skin, and are responsive to sunlight and darkness.”

As the demand for melatonin supplements soars, it becomes all the more crucial to obtain a more comprehensive understanding of the hormone’s effects on our bodies.