Melatonin

Melatonin is better at shifting your body clock than at knocking you out. For sleep onset it saves about 7 minutes on average. Low doses work; labels are often wrong.

• Evidence: Some
• Low effort
• Low cost
• Works: 1–3 days for timing shifts

Why it matters

Your brain releases melatonin in the evening. It tells your body clock that night has started. A supplement can do two things:

• Make you a bit sleepier if taken shortly before bed.
• Move your body clock earlier or later, depending on when you take it. Taken in the afternoon or early evening, it shifts your clock earlier [4].

Where you can buy it

• US: sold as a dietary supplement, which the FDA regulates less strictly than prescription or over-the-counter drugs [7].
• Canada: licensed melatonin natural health products are sold for adults only. Since 2 June 2026, melatonin sold for sleep in children and teens under 18 needs a prescription [14].
• UK: prescription only [8].
• Australia: people over 55 can buy a slow-release form over the counter; everyone else needs a prescription [13].
• Elsewhere: NCCIH says melatonin is a prescription-only drug in several other countries [7].

How to do it

1. Start low. In 30 adults over 50, 0.3 mg taken 30 minutes before bed improved sleep efficiency in those with insomnia. A 3 mg dose also helped but lowered body temperature and kept melatonin levels high into the next morning [3]. Trials in the main meta-analysis used 0.1 to 5 mg in adults [1]. The prescription dose in the UK is a 2 mg slow-release tablet [9].
2. To fall asleep: take it 1–2 hours before bed. That’s the NHS advice for the 2 mg slow-release tablet in short-term insomnia [9].
3. To shift your clock earlier (for travel east, or a body clock that runs late): 0.5 mg worked best taken in the afternoon, about 9–11 hours before the midpoint of your usual sleep [4]. If you sleep 11 p.m. to 7 a.m., your midpoint is 3 a.m., so that’s roughly 4–6 p.m. See jet lag.
4. Use it short term. The NHS says treatment usually lasts up to 13 weeks [8].

Check with a doctor or pharmacist first if you’re pregnant or breastfeeding, have epilepsy, or take any regular medication. The NHS says melatonin isn’t usually recommended in pregnancy because little is known about the effects on babies [12], and NCCIH notes a lack of safety research in pregnancy and breastfeeding [7].

Side effects

Common ones, per the NHS: daytime sleepiness, headache, stomach ache, nausea, dizziness, irritability, and strange dreams [10]. NCCIH says melatonin may stay active longer in older people and cause daytime drowsiness [7]. Don’t drive if you feel drowsy the next morning.

Interactions

The NHS lists these [11]:

• Antidepressants: fluvoxamine and amitriptyline.
• Sedatives and sleeping pills: benzodiazepines (such as temazepam and diazepam), and zolpidem, zopiclone and zaleplon.
• Blood pressure medicines.
• Blood thinners: warfarin. NCCIH says people on blood thinners, and people with epilepsy, should take melatonin only under medical supervision [7].
• Others: opioids (codeine, morphine), NSAID painkillers (ibuprofen, naproxen, diclofenac), oestrogens (the pill, HRT), quinolone antibiotics, rifampicin, carbamazepine, cimetidine, thioridazine and psoralens.

Don’t combine it with sleepy herbal remedies [11]. Never stop a prescribed medicine to take melatonin.

Common mistakes

• Taking 5–10 mg because “more is stronger”. Low doses shift the clock as well as higher ones when timed right [4], and higher doses can leave melatonin in your blood into the morning [3].
• Trusting the label. In 31 products bought in Canada, melatonin ranged from 83% less to 478% more than the label, and 8 contained serotonin [5]. In 25 US gummies, only 3 were within 10% of the label; one had no detectable melatonin [6]. Look for products tested by an independent lab.
• Using it if you already sleep fine. In the 0.3 mg trial, it didn’t change sleep in normal sleepers [3].

Effect on your sleep score

• Time to fall asleep: about 7 minutes shorter than placebo on average [1].
• Total sleep: about 8 minutes longer on average [1].
• Timing: this is where you’d notice it. Well-timed doses move your sleep earlier [4].
• Deep sleep, REM, HRV, resting heart rate: we found no study measuring these in healthy adults with wearables.

How confident: moderate for the small sleep-onset effect; good for timing shifts.

Evidence

Rated Some. A 2013 meta-analysis of 19 trials with 1,683 people found melatonin cut time to fall asleep by about 7 minutes, added about 8 minutes of sleep, and modestly improved sleep quality. Trials that were longer or used higher doses showed larger effects [1]. The American Academy of Sleep Medicine suggests doctors not use melatonin for chronic insomnia (a weak recommendation) [2].

The phase-shifting evidence comes from careful lab studies. In 34 healthy adults aged 18 to 42, 0.5 mg moved the body clock. Compared with an earlier 3 mg study using the same method, both doses shifted the clock by similar amounts when each was taken at its best time [4].

Limits: most trials were in people with sleep disorders, and supplement doses are unreliable [5] [6].

General information for healthy adults, not medical advice. If you have a sleep problem that lasts, read when to see a doctor. Sources checked 4 October 2026. Spot a mistake? Tell us.