The hormone melatonin should not be available on the NHS to help treat jet lag, a review of the evidence has concluded.

Melatonin is a hormone produced in the body during darkness that plays a role in the body clock and helps to regulate sleep cycles.

It is available on the NHS as a treatment for some sleep problems, including in older people and children with attention deficit/hyperactivity disorder (ADHD).

Whether it helps with jet lag is less clear . However in 2019 two melatonin products were licensed as a prescription medication for managing short-term jet lag by the UK’s Medicines and Healthcare Products Regulatory Agency

Now an independent drug review for the hormone by the Drug and Therapeutics Bulletin – a publication that summarises and weighs the evidence for medicines and treatments – has concluded the hormone should not be prescribed for jet lag on the NHS.

“We would suggest that melatonin for jet lag is added to the list of drugs that may not be ordered under a General Medical Services Contract,” the authors wrote.

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The authors looked at the same collection of 14 studies (including 10 randomised placebo-controlled trials) that were submitted to the MHRC, as well as Cochrane reviews – the gold standard for looking at evidence – and other studies of previous research on melatonin for jet lag or to improve sleep.

Most of the clinical trials on melatonin for jet lag, the team noted, were published between 1986 and 2005, and many were small. But as the hormone has been licensed for this purpose for more than 10 years elsewhere in the EU, more modern data was not required by the MHRC.

The team concluded the evidence suggests melatonin does have a modest effect on reducing the symptoms of jet lag – one analysis based on four previously published studies with a total of 232 participants suggested those given melatonin rated their jet lag as 27 on a 100-point scale compared with 45 for those given a placebo.

It also appears generally safe, although it can have side effects including nausea and dizziness. It may also increase the rate of seizures in those with epilepsy and cause problems for those with autoimmune diseases, and is not recommended during pregnancy or breastfeeding.

The team said 30 melatonin tablets of 3mg each costs £65 while 150ml of a 1mg/ml solution costs £130.

However the authors said the evidence base for using the hormone for jet lag remains poor – and in any case jet lag goes away on its own within a few days, and is not a major priority for the NHS.

“The question is, should NHS resources be used to support a short term, self-limiting condition that is generally associated with travel for pleasure and holidays?,” said David Phizackerley, the deputy editor of the Drug and Therapeutics Bulletin.

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Phizackerley said the team’s recommendation does not change the fact that doctors could at present prescribe melatonin for jet lag – although a clinical knowledge summary forthe National Institute for Health and Care Excellence does not advise melatonin for this purpose. But, he said, the review could help to shape guidance should Nice decide to issue it.

Phizackerley said the review was not a criticism of the MHRA. “We are not questioning whether it should have a license, because it is shown to do something and it appears to be relatively safe,” he said.

He added that restricting prescriptions of melatonin so that it is not available for jet lag would prevent a postcode lottery. “It would make it a lot easier for patients, because everyone would know then that it is not available [on the NHS],” he said.

Dr Neil Stanley, an independent sleep expert and author of How to Sleep Well, said while there is some evidence showing a melatonin is beneficial for jet lag, studies vary widely in the dose that seems to have an effect, while correct timing of doses is complex. Large-scale studies, he added, would be expensive to run with little profit in return.