How safe is melatonin?

Yes

Melatonin is “a naturally occurring hormone, produced by the brain, which signals that it is time to sleep”, says Professor Guy Leschziner, a consultant neurologist specialising in sleep disorders at Guy’s and St Thomas’ Hospitals. “As such it is intrinsically different to sedatives, which suppress the central nervous system and slow brain activity, and can be associated with memory issues. It is generally safe and non-addictive.” It’s usually sold as tablets or in gummy form, though regulation of it varies: in the UK and Denmark, for example, it is prescription-only because it’s classified as a medicine rather than a supplement. In countries such as the US, Spain and France it is available over the counter. 

Treating it like a knockout pill won’t work

Many people find melatonin helps them “fall asleep more quickly, and improves overall sleep quality”, says Dr Federica Amati, head nutritionist at Zoe and nutrition topic lead at Imperial College London School of Medicine. “It’s especially effective for short-term insomnia and disrupted sleep patterns such as those caused by shift work or long-haul travel.”

A typical dose might start at 1mg, and should be taken around 90 minutes before your target sleep time. Amati recommends “starting low at 1mg-2mg and only increasing if needed. Evidence suggests a typical effective dose is between 2mg and 4mg. Higher doses do not reliably improve results.”

For travel, you might shift your dose (and target sleep time) closer to the bedtime of your destination for two or three nights before you fly and then dose at the local bedtime for the first few nights after you arrive. Dr Harpal Bains, founder of the Harpal Clinic, suggests avoiding taking melatonin for more than three to four weeks without medical advice “as mistimed or unnecessary use can worsen sleep”. Because timing and dosage are important, the experts I interviewed recommend seeking medical advice before taking.

Bains notes that in helping people to access quality sleep sooner, “melatonin may indirectly boost the release of growth hormone, which in turn helps maintain bone and lean muscle mass”. It also “supports healthy mitochondrial function, and hence can play a wider role in cellular repair and regeneration”. Adds Amati: “It is anti-inflammatory and will strengthen the intestinal barrier, which is essential to good gut health and immune system function.”

No

“The surge in use of melatonin in various forms gives an image that we should be ingesting it without worry,” says Dr Madusha Peiris, a senior lecturer in neuroscience at Queen Mary University of London. She warns against higher doses – more than 10mg, according to NHS guidelines – as these can cause grogginess and vivid dreams. She also points out that studies concerning long-term use are currently embryonic.

People hoping to use melatonin like a sedative will be disappointed, says Bains. “It works best for circadian rhythm problems or jet lag; treating it like a knockout pill won’t work. Instead, the best way to optimise melatonin levels is to observe dark/light cycles as much as possible – no screens close to bedtime, or at least use blue light filters – eat well, and support gut health.” Pro-sleep alternatives she recommends include supplements such as magnesium, glycine and tart cherry extract. (All of which are combined in Ben Ainslie’s Ainslie + Ainslie Night Powder and Cytoplan’s Cyto-Night.) 

Those with existing health conditions should seek medical advice before using melatonin as there are risks of negative drug interactions. There is also insufficient trial evidence that it is safe to take during pregnancy. For long-term issues with sleep, says Leschziner, drugs of any kind may not be the best option. “The gold standard treatment for treating sleep disorders within the NHS is Cognitive Behavioural Therapy for Insomnia [CBT-i], a course teaching techniques in retraining the brain to associate bed with sleep. It’s a proven treatment with high efficacy and, unlike pills that only work while you’re taking them, CBTi continues to work after you’ve gone through that treatment.” It is available through apps such as CBT-i Coach, or via Zoom from Sleep Well Oxford.