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6 Ugly Side Effects of Taking Melatonin Before Bed

Beware of this nighttime routine—it may cause more harm than good.
FACT CHECKED BY Alexa Mellardo

Did you know that your brain naturally creates the hormone melatonin when you're in a dark environment? The hormone supports your body's circadian rhythms, as well as daily sleep, according to the National Institutes of Health. That being said, because sleep isn't perfect or consistent for everyone a lot of the time, many choose to supplement in hopes it can be improved.

One of the main powers of a melatonin supplement is that it can support better, deep sleep. "Melatonin is generally safe when taken in low dosages and is for short-term use only," suggests Deena Adimoolam, MD, a member of the Eat This, Not That! medical expert board and specialist in endocrinology and metabolism. While over-the-counter melatonin is generally safe to use in moderation, you should still ask your doctor if it's best for you and your individual body, she goes on to explain. Because whether it's in the form of a gummy or a capsule, it's possible that this bedtime supplement has the potential to cause you harm or ugly side effects.

There are always dangers when it comes to taking any supplements to fill in any gaps for the needs of your body. And that still includes those that are made up of natural or organic compounds, such as melatonin. So, before you get all cozy in bed and pull up the covers, make sure that your nighttime routine isn't negatively affecting your health. Read on to learn more about the ugly side effects of melatonin, and next, check out The 5 Healthiest Supplements to Take, According to Doctors.

It can cause short-term side effects

woman dealing with severe headache or migraine at home

While the back of medicine bottles will usually contain a long list of unwanted possibilities, melatonin is no different. Talk about ugly side effects—your body may end up paying the consequences.

Common side effects of melatonin usage include headaches, dizziness, nausea, and drowsiness, per Mayo Clinic. For the most part, studies that noted these symptoms were reportedly mild and short-term.

"Long-term risks of melatonin use [are] unknown, as most research studies have evaluated short-term use only," Adimoolam says. Even though there haven't been any studies that acknowledge any long-term effects, there is still much more research to be done to clarify there aren't any for certain.

It can cause vivid dreams or nightmares

having bad dreams

Melatonin may improve your ability to catch some Z's, but for some people, an unfortunate side effect is that your sleep will be tainted by unwanted visuals. Vivid dreams and nightmares may take place, according to Mount Sinai researchers, and this can be a result of taking too much melatonin (possibly too frequently as well). Studies have found that since the supplement can disrupt circadian rhythms (or your "body clock"), your body may be in REM sleep—the sleep cycle known for vivid dreaming—longer than normal.

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It can interfere with certain medications

melatonin pills sleep concept

It's important to always review your medications before you add something new to the mix. If you have any serious health conditions, taking melatonin may not be a good option to begin with.

Melatonin has been seen to negatively interact with certain medications—such as blood thinners and anti-seizure medications—which is a major downside to the supplement, explains Adimoolam. It's not uncommon for these types of medications to hinder the body's natural ability to curate melatonin hormones, which is why supplementing may seem like the next step.

However, in terms of blood-thinning medications (anticoagulants), taking melatonin has been linked to a potential increased risk of bleeding. Alongside that, melatonin supplements can enhance one's chance of having seizures, as well as increase how often those seizures may occur (especially in children) if neurological disabilities are present, according to Mayo Clinic.

It can lower your energy levels and mood

woman sad in bed, side effects of melatonin

Dealing with pre-existing mental health conditions on a daily basis is challenging enough as it is. Unfortunately, Adimoolam explains, "Individuals with known mood disorders like depression may experience worsening depressed mood and/or anxiety." Melatonin can lower one's mood and energy levels—in the process of relaxing and preparing the body for sleep—which can mimic or foster a depressive state in people who already suffer from the illness.

Although, some experts have reported that you can attempt to counteract the negative toll melatonin takes on mental health by increasing your vitamin D intake. Since vitamin D is a natural way to improve one's mood, it may help some. But many who still experience excessive mood changes must stop taking the supplement altogether and discuss uneasy sleep patterns with a doctor.

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It heavily affects the elderly

elderly woman taking melatonin supplement before bed

Out of all users, "elderly people may be more sensitive to melatonin and more likely to develop side effects, most especially drowsiness and lethargy," according to Adimoolam.

In 2015, The American Academy of Sleep Medicine guidelines stated that the elderly who suffer from dementia should not take melatonin. The effects on the body's circadian rhythms tend to last longer in older people, resulting in uncontrollable daytime drowsiness.

It can keep you up at night if you take too much

woman having trouble sleeping during menopause

Ironically, melatonin can end up causing you to get no sleep at all. If your dosage of melatonin is too high, it can lead to a "state of enhanced alertness," Medical News Today reports, which is quite the opposite of what you're trying to achieve when you snuggle up in bed after a long day's work.

A previous version of this article was originally published on May 4, 2022.

Jordan Summers-Marcouillier
Jordan Summers-Marcouillier was born and raised in San Jose, California and now works as a writer in New York, NY. Read more about Jordan