Many of us struggle to fall asleep. Increased time spent in front of screens, irregular sleep schedules and work or life stresses running through your mind can all make switching off at night difficult.
Sleeping pills can feel like a drastic measure or a last resort, which may make melatonin seem like an appealing alternative. After all, melatonin is naturally produced by your body to help regulate sleep — so does that mean taking it as a supplement is an effective and harmless way to get a better night's sleep?
What is melatonin and what does it do?
Melatonin is a hormone produced by the pineal gland in your brain. Its production is closely linked to light: darkness stimulates melatonin release, while light suppresses it. This is one reason why exposure to bright light, including screens, late in the evening can interfere with your natural sleep-wake cycle.
Melatonin release follows your body's circadian rhythm, with levels typically rising in the evening and peaking during the night. Rather than acting like a traditional sleeping pill that simply makes you drowsy, melatonin acts as a signal to your body that it is nighttime and helps regulate when you feel ready to sleep.
Taking a melatonin supplement increases the amount of melatonin circulating in your body, mimicking this natural signal.
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Is it safe to take melatonin every night?
In the UK, melatonin is a prescription-only medicine. In the US, however, it is widely available over the counter as a dietary supplement, often in doses ranging from a few milligrams upwards.
So what happens if you take it every night?
The evidence available so far is relatively reassuring. Studies have not found clear evidence that melatonin loses its effectiveness with continued use, and a review examining studies of at least six months' duration found a low frequency of adverse events associated with longer-term use.
Reported side effects are generally mild and can include daytime sleepiness, headache, dizziness and nausea.
However, there is an important caveat: there are relatively few high-quality, double-blind trials investigating people taking melatonin continuously over long periods. This means that the absence of evidence of serious harm shouldn't be interpreted as definitive proof that taking melatonin every night for years is completely risk-free.
So, should you take melatonin to help you sleep?
Melatonin isn't a miracle sleep aid, but neither is it ineffective. The evidence suggests it can help people fall asleep slightly faster and sleep a little longer, with relatively few reported side effects.
What is less certain is the benefit of taking it routinely every night, particularly if you are otherwise healthy and simply struggling with poor sleep. Melatonin plays an important role in regulating the timing of sleep, but taking more of it cannot compensate for all the other factors that influence how well we sleep.
For occasional problems such as jet lag, or for certain sleep and circadian rhythm disorders, melatonin can be useful. But if you regularly struggle to fall or stay asleep, it is worth considering the underlying reason rather than automatically reaching for a nightly supplement.
Ultimately, the fact that melatonin occurs naturally in the body doesn't automatically make taking it as a supplement harmless. The evidence we have so far is reassuring, but when it comes to taking melatonin every night for years, there is still more we need to learn.
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Who should be cautious about taking melatonin?
Although melatonin is generally considered safe for short-term use, it isn't suitable for everyone. Pregnant or breastfeeding women are generally advised to avoid melatonin unless recommended by a healthcare professional, as there is not enough research to establish its safety during pregnancy or breastfeeding. People taking certain medications should also be cautious, as melatonin can interact with medicines including blood thinners and some epilepsy medications. If you have a medical condition, take regular medication, or are pregnant or breastfeeding, it is worth speaking to a healthcare professional before taking melatonin regularly.
References
National Center for Complementary and Integrative Health. Melatonin: what you need to know. Available at: https://www.nccih.nih.gov/health/melatonin-what-you-need-to-know (Accessed: 21 September 2026).
Amaral FGD, Cipolla-Neto J. Physiology of the pineal gland and melatonin. In: Feingold KR, Anawalt B, Blackman MR, et al., editors. Endotext. South Dartmouth, MA: MDText.com, Inc.; 2000–. Available at: https://www.ncbi.nlm.nih.gov/books/NBK550972/ (Accessed: 21 September 2026).
Kunz D, Mahlberg R, Müller C, Tilmann A, Bes F. Melatonin in patients with reduced REM sleep duration: two randomized controlled trials. The Journal of Clinical Endocrinology & Metabolism. 2004;89(1):128–134. doi: 10.1210/jc.2002-021057.
Ferracioli-Oda E, Qawasmi A, Bloch MH. Meta-analysis: melatonin for the treatment of primary sleep disorders. PLoS ONE. 2013;8(5):e63773. doi: 10.1371/journal.pone.0063773.
Besag FMC, Vasey MJ. Adverse events in long-term studies of exogenous melatonin. Expert Opinion on Drug Safety. 2022;21(12):1469–1481. doi: 10.1080/14740338.2022.2160444.
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