A small test of 10 melatonin pills bought in the U.S. found that 4 of them had way more or way less melatonin than what was printed on the bottle — so you might not be getting what you think you're paying for.

Some melatonin pills you can buy in the U.S. have strange, unknown chemicals in them—up to 1% of the pill—which isn't supposed to be there, even though they pass safety checks for the stuff they're supposed to contain.

In the U.S., you can buy melatonin pills without a prescription, but they’re not checked like real medicines—so some pills might have way more or less melatonin than the label says, or even contain weird stuff you didn’t sign up for.