Melatonin for sleep: does it work, and can you get it in the UK?

What is melatonin?

Melatonin is a hormone made by the pineal gland in the brain. Levels rise in the evening as light fades and stay high through the night, which tells the rest of the body that it’s night-time. Bright light, especially in the evening, holds it back. It’s part of the body clock, not a sedative: it signals when to sleep rather than knocking you out.

How much does it help insomnia?

Not much. A 2013 review pooled 19 trials with 1,683 people who had sleep problems with no other medical cause. Compared with placebo, melatonin:

• cut the time to fall asleep by about 7 minutes,
• added about 8 minutes of total sleep,
• slightly improved how well people rated their sleep.

The effects were statistically real but small. US sleep medicine guidelines advise against melatonin as a treatment for chronic insomnia in adults, because the benefit is so modest. It may help more when the problem is timing, for example a body clock that runs late.

Does it help with jet lag?

Probably, and this is where the evidence is best. The NHS doesn’t recommend it for jet lag, saying there isn’t enough evidence, but a 2002 Cochrane review found that in 9 of 10 trials, melatonin taken close to the target bedtime at the destination reduced jet lag after flights across five or more time zones. Doses from 0.5 to 5 mg worked similarly, though 5 mg helped people fall asleep faster. See our guide to jet lag.

Who can get it in the UK?

Melatonin is prescription only. According to the NHS, it is mainly prescribed for short-term sleep problems in people aged 55 and over, usually for up to 13 weeks. Specialists also prescribe it for some children. UK brands include Circadin, Adaflex, Ceyesto, Slenyto and Syncrodin.

What are the side effects?

The most common are headache, tiredness the next day, feeling sick and irritability. The NHS advises:

• Don’t drive or use tools if you feel sleepy after taking it.
• Avoid alcohol, which reduces how well it works. Smoking does too.
• Don’t take it with herbal sleep remedies.
• Tell your doctor about other medicines, as some interact with it, including fluvoxamine and some blood thinners.

Why not buy it online?

Melatonin sold as a supplement abroad isn’t held to medicine standards. When researchers tested 31 products in Canada, the melatonin content ranged from 83% below to 478% above the label, and more than 7 in 10 products were off by more than 10%. Eight contained serotonin, which wasn’t listed. Doses also vary wildly, from 0.5 mg to 10 mg or more, and more is not better.