Melatonin Supplements: What to Know
Melatonin is the hormone your body makes in the dark to signal that night has arrived, and its supplements are among the most popular sleep products in any pharmacy aisle. The marketing can make it sound like a magic switch, but the truth is more specific: melatonin nudges the body clock rather than forcing sleep. It has genuine uses, and knowing when it helps and when it does nothing saves a lot of disappointment.
What melatonin actually does
Melatonin is produced by the pineal gland in the brain as light fades, rising through the evening and falling through the night. Its job is to tell your internal clock that it is night, which sets the stage for sleepiness. It does not act like a sedative that knocks you out; it opens the door to sleep by signalling the right time. That is why the supplement works best when the body clock needs correcting rather than when you simply need to be asleep.
What the evidence shows
The strongest evidence for melatonin is in jet lag, where taking it at the target bedtime helps the clock adjust to a new time zone. It also has a role in delayed sleep phase, the pattern where sleepiness arrives very late at night, by moving the clock earlier when timed well. For plain insomnia in adults, the results are modest: it may shave a little time off falling asleep for some people, but it is not the powerful sleep medicine many expect.
Dosing and timing
With melatonin, timing beats dose. Taking a small dose around an hour before the target bedtime, following the product's instructions, is the standard approach, and more is not better; higher doses can leave you groggy and do not improve the shift in the clock. It matters which product you use, because strengths and licensing differ, and in the UK melatonin is a prescription medicine for some uses, so a pharmacist can advise on what applies in your situation.
Who might benefit
- Travellers crossing several time zones who want help adjusting their body clock
- People with a confirmed delayed sleep phase under professional guidance
- Shift workers, used carefully, to help anchor daytime sleep in a dark room
- Some children with certain neurodevelopmental conditions, but only on specialist advice
If the issue is ordinary difficulty falling asleep from a busy mind or poor routine, the foundations in our sleep hygiene guide are likely to do more than melatonin.
Safety and side effects
Melatonin is generally well tolerated for short-term use, though some people get headaches, dizziness or vivid dreams, and morning grogginess if the dose is too high. Long-term effects are not fully mapped, so it is best treated as a short-term tool rather than a permanent nightly habit. It should be avoided in pregnancy and breastfeeding, and it can interact with blood-thinning medicines, so always check with a pharmacist or GP first.
Melatonin versus prescription sleep medicines
| Melatonin | Prescription sleeping tablets |
|---|---|
| Signals the body clock, not a sedative | Act directly on the brain to promote sleep |
| Low risk of dependence | Tolerance and dependence can develop |
| Best for timing problems and jet lag | Best for short-term insomnia under supervision |
| Modest effect on sleep onset | Usually faster, more powerful sleep onset |
Prescription sleep medicines such as zopiclone work differently and are only available after a proper assessment, as our article on zopiclone explains, and the wider comparison of options is in our guide to sleep medicines FAQs.
For travellers in particular, pairing melatonin with the light guidance in our jet lag recovery article is far more effective than either alone, because light is the stronger signal and melatonin just reinforces it.