Supplements and a clock on a light blue background.
Photo: Getty Images

First, a shopper’s tip: A seal from a group like the U.S. Pharmacopeia or ConsumerLab.com provides some assurance that supplements contain what their labels claim. Here’s what to look for on the bottle before you buy.

Melatonin

This popular supplement is made from a natural or synthetic version of the hormone melatonin, which signals to your body that it’s time to sleep. It can be helpful for older adults (who produce less melatonin) and those with wonky body clocks (night owls, jet-lagged travelers, and night-shift workers).

But a 2013 meta-analysis found that, on average, people fall asleep only about 7 minutes faster after taking melatonin. Talk to your doctor before trying this supplement, and consider taking it only occasionally: Research is still pending on the safety of long-term use, beyond about three months.

Iron

Iron deficiency is closely linked to restless legs syndrome, a condition marked by uncomfortable sensations in the limbs and an uncontrollable urge to move them—which can interfere with sleep. Think this might be your issue? Consult a doctor before self-treating. Taking iron could mask a more serious problem. Plus, in people without a deficiency, supplementing could lead to iron overload, which can damage organs.

Vitamin D

A growing body of evidence suggests a link between low levels of vitamin D and sleep troubles. 

More on Sleep

One study of 89 adults with sleep disorders, published in 2018, found that when people whose vitamin D levels were on the low side, but not deficient, took supplements regularly for eight weeks, they said they nodded off faster, slept longer, and had better sleep quality than those who received a placebo.

But other research has found that in certain populations, the supplements have no positive effect on sleep, or may worsen it. What to do? Talk to your doctor about vitamin D testing and whether supplements might be worth a try.

Valerian

This root has been used for centuries to treat insomnia. And several studies suggest that this supplement may help people fall asleep faster and wake up less often at night—though next-day grogginess may occur. But other studies show no benefit. Such mixed findings may be due to the variable quality and instability of active ingredients in valerian, according to a 2020 research review, so be sure to check for a trustworthy seal on the bottle.

Editor’s Note: This article also appeared in the February 2022 issue of Consumer Reports magazine.