Melatonin questions, answered

Melatonin is a hormone made mainly by the pineal gland in the brain. Its levels rise in the evening as light fades and fall towards morning, helping signal night-time to the body clock.

Research has used a wide range of amounts, from fractions of a milligram to several milligrams. In the UK, the prescribed prolonged-release tablet for adults aged 55 and over is 2 mg. The right amount for any individual is a question for a pharmacist or GP, and more is not necessarily better.

Standard melatonin taken by mouth has a short half-life, commonly described as under an hour, so most of it is cleared within a few hours. Prolonged-release forms are designed to release melatonin gradually over several hours.

Standard forms are absorbed fairly quickly, which is why products are usually taken shortly before the planned bedtime. Timing relative to your own body clock matters as much as the amount.

Reported side effects are usually mild and short-lived, most commonly headache, dizziness, daytime sleepiness and nausea. Vivid dreams are also reported by some people.

Taking melatonin late, or using a slow-release form close to your waking time, can leave some melatonin active in the morning. Individual sensitivity varies.

For short-term use in healthy adults, research generally reports a good safety profile. Long-term evidence is more limited, and some groups should seek advice first.

Yes, it can interact with some medicines, including certain blood thinners, sedatives and drugs affected by liver enzymes. A pharmacist can check your medicines.

Jet lag is one of the best-studied uses of melatonin. Reviews have found it can reduce jet lag symptoms, especially when travelling east across several time zones.

No single form is best. Tablets are the most consistent, gummies are the most convenient, and drops make small amounts easy to measure.

No. Melatonin acts mainly as a timing signal for the body clock rather than sedating the brain the way traditional sleeping pills do.

These are specialist situations. Melatonin for children in the UK is normally started by a specialist, and there is not enough evidence on use during pregnancy or breastfeeding.