Is it safe

Can you take melatonin every night?

By GyroscopeUpdated November 14, 20268 sources

Short courses look low-risk, and in trials the effect didn’t fade with nightly use. But most safety trials lasted 4 weeks or less, so nobody knows much about years of it. Run a two-week test, and keep taking it only if your own nights show it working.

It’s easy to start melatonin for one bad week and still be taking it a year later. It’s cheap, it’s sold next to vitamins, and the jar is always on the nightstand. US adult use went from 0.4 percent around 2000 to 2.1 percent by 2018, a fivefold rise.

We’d treat nightly melatonin like anything else you take every day. Every so often, check that it’s doing something. Two weeks alternating on and off, judged on one measure you pick before you start, shows whether it helps you.

It’s like glasses you’ve never had checked. They might be helping, but you’ll only know by trying a day without them.

What the trials say about nightly use

In a 2013 analysis of 19 trials with 1,683 people, melatonin cut about 7 minutes off the time to fall asleep and added about 8 minutes of sleep. The authors found the effect didn’t wear off with continued use, and longer trials showed bigger effects. In a 1995 trial in older adults with insomnia, two months of nightly slow-release melatonin kept working, with no sign of tolerance, and their sleep got worse again when they stopped.

Taking it also doesn’t seem to switch off your own supply. In 21 night shift workers who took 0.5 mg at bedtime for a week, their own melatonin came back at the same height afterward.

What nobody knows yet

A 2019 review of 37 trials, at 0.15 to 12 mg a day, found side effects were mostly mild, and nothing life threatening. Most of those trials lasted 4 weeks or less and the longest about 29 weeks, and the authors said the lack of long-term trials limits what anyone can say about continuous use over long periods. The US National Center for Complementary and Integrative Health says short-term use looks safe for most people and that information on long-term safety is lacking.

The heart failure headline from November 2025 came from people with melatonin in their records for a year or more. It couldn’t separate melatonin from worse insomnia and hadn’t been peer reviewed, and the heart answer goes through it.

If it’s for insomnia that won’t go away

The American Academy of Sleep Medicine’s 2017 guideline suggests doctors don’t use melatonin for long-term insomnia in adults, a weak recommendation. The American College of Physicians recommends cognitive behavioral therapy for insomnia (CBT-I) as the first treatment. If you’ve needed something every night for months, it’s a good reason to see a doctor, alongside the test below.

The two-week test

Pick one measure before you start, such as minutes to fall asleep from a morning note, or total sleep from a ring or watch. Alternate a week off and a week on. Leave out nights with drinks or a late night. If the on nights beat the off nights by more than your normal night-to-night swing, keep it. If they don’t, you can stop. The tool below does the math.

Don’t drive after a dose.