Should you take melatonin?

Melatonin can help when your problem is timing: jet lag, or a body clock that's shifted so late you can't fall asleep until 2 or 3 in the morning ¹. If you've been lying awake for months, that's something else. For that kind of insomnia, doctors' guidelines don't recommend melatonin, because there isn't good enough evidence that it works or that it's safe ¹.

If timing is your problem, I'd look at the light in your day before you buy a bottle. Light moves the same body clock that melatonin does ², and you can start working on it tomorrow morning.

What melatonin does

Melatonin is a hormone your brain makes when it gets dark ¹. Your levels start to climb about two hours before your usual bedtime, and daylight keeps them low all day ². It helps set the timing of your sleep and of your body clock, the 24-hour clock inside you ¹.

A melatonin pill can move that clock too, and which way it moves depends on when you take it. Taken in the early evening, hours before your usual bedtime, it moves your clock earlier. Taken in the morning, after your usual wake-up time, it moves it later. At the wrong time, it can make a timing problem worse ².

Start with the light in your day

Light at night can block melatonin ¹. Bright light in the morning moves your body clock earlier, so your own melatonin starts rising earlier in the evening too ². So get outside soon after you wake up, even if it's only to walk the dog or walk the kids to school. In the evening, keep the room you're in lit by a lamp instead of the bright ceiling light, and keep your phone dim, so there's less light holding your melatonin back.

If you can't fall asleep until 2 or 3 a.m.

If you go to bed at a sensible hour, lie there for ages and would sleep half the morning if nobody woke you, your body clock may be running late. When a doctor finds that it's a sleep disorder, melatonin seems to help with sleep ¹. But it isn't clear yet that the help is worth the possible harms ¹.

In one small trial, adults with a diagnosed late body clock took melatonin every evening and were told to go to bed earlier and dim their lights before bed, and after four weeks the body clocks that were measured ran nearly 90 minutes earlier on average ³. Nobody got a dummy pill, so there's no telling how much of that came from the melatonin ³. I'd keep up the light changes alongside it if a doctor does put you on melatonin, since in that trial the pill was never tried without those dimmer lights.

Melatonin for jet lag

Melatonin may also ease jet lag after flights east or west ¹. Flying east, you need your clock to run earlier, and flying west, you need it later, so the time you take it has to match the direction you flew ². Get it backwards and it can leave you more out of step than before ². Light moves the same clock when you travel ². So on a trip, time your sun and your sunglasses as carefully as you'd time the pill.

Is melatonin safe?

For a short stretch, it looks safe for most people, but very little is known about taking it for months or years. In short studies of adults, the side effects were mild: headache, dizziness, nausea and sleepiness ¹.

In the U.S., melatonin is sold as a dietary supplement, which the FDA regulates less strictly than medicines ¹. In several other countries you need a prescription for it ¹. Researchers who tested 25 different kinds of melatonin gummies bought in the U.S. found that 22 didn't have the amount on the label. One had none they could detect, and the rest ranged from about three-quarters to more than three times what the label said ⁶. An earlier test found serotonin, a hormone that can cause harm even at fairly low levels, in about a quarter of the supplements it checked ¹.

If you've been lying awake for months

If you've had trouble falling asleep or staying asleep at least 3 nights a week for 3 months or more, that counts as long-term insomnia ⁴. For that, the first step is cognitive behavioral therapy for insomnia, or CBT-I for short ¹.

It takes 6 to 8 weeks, and you don't have to sit in an office for it. You can do it with a doctor, a nurse or a therapist, in person, over the phone or online ⁵. Part of it is changing what you do in bed. You only go to bed when you're sleepy, you get up if you can't sleep, and you start with a set amount of time in bed that grows as your sleep gets better ⁵.