Melatonin is a hormone that our brains produce at night to tell the rest of the body to wind down. When your natural levels of melatonin are low, taking a synthetic version of the hormone (and 99% of melatonin supplements are synthetic) essentially tricks your brain into thinking it’s bedtime.
As such, Ferira explains, the most compelling use of melatonin supplements is to overcome an anomaly in your body clock (circadian rhythm), like when you’re traveling to a new time zone or acclimating to a night shift at work. As far as enhancing sleep quality on a nightly basis, though, she says the research just isn’t there.
She also warns that taking a hormone nightly can lead to desensitization and cause you to need higher and higher doses in order to feel any effect. Over time, this may throw off your body’s natural production and levels of melatonin, as well as other important hormones.
“I have not seen good data to show that high doses of melatonin will not impact your endogenous, natural production of melatonin,” Ferira says on the podcast. In fact, so far preliminary studies are showing just the opposite: A preclinical study in Nature recently found that supplemental melatonin may negatively affect thyroid health, while other research has shown it can inhibit the function of hormones like estrogen and male growth hormone.
“I think there’s more research to be done here,” concludes Ferira. But until we have a better idea of the long-term effects of melatonin supplementation, she doesn’t recommend taking the hormone nightly unless otherwise instructed by an endocrinologist.