For most adults, a small dose is usually enough: commonly 0.3 mg to 1 mg, taken about 1 hour before bed; many OTC products are 3 mg or 5 mg, but bigger isn’t usually better. Melatonin is generally used for trouble falling asleep, and it’s best to start low and only increase if needed and if it’s safe for you.

Typical dosing

  • Adults with short-term sleep problems: 2 mg slow-release is a common prescription dose in the UK, taken 1 to 2 hours before bedtime.
  • OTC sleep supplements: Many experts suggest starting at 0.3 mg to 1 mg and using the lowest effective dose.
  • Upper end: Doses above 5 to 10 mg are usually not needed for routine sleep use, and higher doses can increase side effects.

How to take it

  • Take it about 30 to 60 minutes before bed for sleep-onset problems.
  • If it’s slow-release , follow the label or prescription instructions; in the NHS guidance, it’s taken 1 to 2 hours before bedtime.
  • If you wake up groggy in the morning, the dose may be too high or taken too late.

Safety notes

  • Common side effects can include daytime sleepiness, headache, dizziness, or mood changes.
  • Don’t combine melatonin with other sedating medicines without checking first, and talk with a clinician if you’re pregnant, have liver disease, or take regular medications.
  • If you need melatonin every night or your insomnia keeps going, it’s worth getting evaluated for an underlying sleep issue.

Practical starting point

A sensible first try for many adults is 0.5 mg to 1 mg, 30 to 60 minutes before bed. If that doesn’t help after a few nights, the next step is usually a careful adjustment rather than jumping straight to a high dose.

TL;DR: Start low, usually 0.3 mg to 1 mg , taken about 1 hour before sleep ; avoid assuming that more melatonin will work better.