5 Myths and Truths About Melatonin and Sleep Meds

By Maria Masters |

Over-the-counter sleep aids may be popular, but they’re not always effective. Here’s what you need to know before nodding off.

Myths and truths about melatonin and sleep meds

It’s no secret that as we age, sleep becomes a little more elusive. We tend to wake up earlier in the morning and wake up more often in the middle of the night. Meanwhile, some of us are also prone to bouts of insomnia, waking up the next morning feeling anything but well-rested.

About one in three older adults log fewer than seven hours of sleep per night, according to a 2022 BMC Public Health study, with about 13% of them experiencing frequent insomnia. What’s more, of those with insomnia, nearly half of the people reported using a sleep aid regularly, including prescription and over-the-counter medications.

But here’s the thing: Some sleep aids can be more like sleep crutches. Not only can some of them make certain sleep disorders worse, but they may also cause potentially harmful side effects, says Aatif M. Husain, M.D., the division chief of epilepsy, sleep, and neurophysiology at Duke University School of Medicine.

Here are the facts — and myths — about some of the most popular sleep aids on the market.

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Myth: Melatonin Doesn’t Have Any Side Effects

Melatonin is a naturally occurring hormone that helps prime your body for sleep. Over the past 10 years, melatonin has risen in popularity as a sleep aid, partly because it has a reputation of being completely benign, says Dr. Husain.

While melatonin is considered relatively safe for adults (at least in the short-term), it can cause side effects like headaches, dizziness, and nausea. Moreover, in older adults, melatonin may stick around in the body longer than it does in younger adults, where it can cause drowsiness the next day, according to the National Center for Complementary and Integrative Health.

Melatonin can also interfere with certain types of medications, including blood thinners, immunosuppressants, and high blood pressure and diabetes medications, according to Mayo Clinic. It’s not known what impact melatonin has on your health in the long term.

Truth: You May Be Taking Too Much Melatonin

As we age, our bodies stop producing as much melatonin as they once did. But that’s not necessarily a reason to take it in supplement form.

Your brain naturally produces micro-milligram levels of melatonin, says Dr. Husain, “so even when you take a small dose, which is 1 milligram, you’re taking way more melatonin than your brain is actually producing.”

While there’s no official recommendations for melatonin use, a typical dose falls in the 1- to 5-mg range. And yet, most people take about 5 to 10 milligrams of melatonin at a time, says Dr. Husain.

Case in point: Researchers in a 2022 Journal of the American Medical Association study found that three times as many people were taking more than 5 mg of melatonin by 2018 than they were in 2005 and 2006. (Before 2005, there were no reports of people taking more than 5 mg.)

But different doses of melatonin can cause different effects. For example, taking more than 1 mg of melatonin will help you nod off faster — usually within about an hour, says Dr. Husain, whereas taking less than 1 mg will help regulate your circadian rhythm.

“If you’re waking up too late in the morning or going to bed too late, the melatonin can help you adjust to that time,” he says.

Recommended reading: The Best Medicine? A Good Night’s Sleep

Truth: You Can’t Necessarily Trust the Label

Dietary supplements aren’t as strictly regulated by the U.S. Food & Drug Administration as, say, prescription medications. So, there’s no guarantee that what’s on the supplement label matches what’s in the bottle.

A study published in the Journal of Clinical Sleep Medicine tested 30 different melatonin supplements and found that the amount of melatonin in the in the bottles was sometimes up to 478% higher and 83% lower than what was claimed on the label.

Myth: Other Herbal Sleep Supplements Are Harmless

Melatonin isn’t the only supplement that people turn to for a better night’s sleep. Some people swear by supplements that contain valerian (a type of grassland plant), ashwagandha (an herb), and kava (a shrub).

The problem? Research hasn’t shown these supplements are always effective at helping people sleep better. In fact, some evidence suggests they can be dangerous in certain circumstances.

Valerian, for example, can cause headaches, dizziness, stomach problems, or even (ironically) sleepiness, according to Mayo Clinic. Ashwagandha can cause headaches, nausea, and stomach problems. Kava can cause dizziness and stomach problems. Most concerning, kava has also been linked to sometimes serious or even fatal liver damage.

Myth: Antihistamines Can Double as Sleep Aids

Antihistamines — which are used to treat allergies — can make you drowsy. This side effect is exactly why some people use them to nod off faster.

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But taking them regularly for a sleep condition like insomnia can cause dependence. Meaning, the longer you take them, the less effective they’re likely to be, according to Mayo Clinic.

One study, published in the Journal of Clinical Sleep Medicine, found that when people took diphenhydramine, they developed a tolerance to the daytime sedative effects of the medication after just three days.

Antihistamines can also worsen restless legs syndrome (RLS). It’s a condition in which people have an uncontrollable urge to move their legs, which interferes with their sleep, says Dr. Husain. (Adults aged 60 and over are about two to three times more likely to have RLS than younger adults, according to a review published in 2019.)

Popping an antihistamine can also cause side effects that linger into the next day, like fatigue, he says. For older adults, some of these medications can also cause dizziness, confusion, hallucination, trouble urinating, and a rapid heart rate, according to Mayo Clinic.

“If you’re taking an antihistamine on an as-needed basis, or rarely, you may not have those problems,” says Dr. Husain. “But if you’re taking it regularly, it can be a pretty big issue.”

The bottom line: Just because a supplement or medication can be found over the counter doesn’t mean it’s right for you. Always ask your doctor whether it’s safe to take a particular sleep medication, says Dr. Husain.

See our sources:
Prevalence of sleep problems among older adults: BMC Public Health
Melatonin side effects: Mayo Clinic
Melatonin overview: National Center for Complementary and Integrative Health
Older adult melatonin use: Journal of the American Medical Association
Study on variability of melatonin content: Journal of Clinical Sleep Medicine
Valerian overview: Mayo Clinic
Ashwagandha overview: Memorial Sloan Kettering Cancer Center
Kava overview: National Center for Complementary and Integrative Health
Antihistamines for insomnia: Mayo Clinic
Study on tolerance to sedative effects of antihistamines: Journal of Clinical Sleep Medicine

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