Melatonin

Melatonin tells the body it is night-time. It is most useful for shifting the body clock — jet lag and delayed sleep phase — where timing matters more than dose. For ordinary insomnia, its average effect is small compared with cognitive behavioural therapy for insomnia, which is the first-line treatment.

Supplements are synthetic melatonin in immediate-release or prolonged-release forms. Gummies are popular and have been a particular source of content inaccuracy and of accidental ingestion by children.

Melatonin binds receptors in the brain's master clock, shifting circadian timing and promoting sleepiness when taken at the right time of day.

Trials and guidance support melatonin for jet lag and for delayed sleep-wake phase when correctly timed. For chronic insomnia, meta-analyses show it shortens time to fall asleep by roughly a few minutes on average, and professional guidance places behavioural therapy ahead of it. Paediatric use has been studied mainly in neurodevelopmental conditions under specialist care.

Laboratory and animal research describes receptor pharmacology, circadian phase shifting and antioxidant properties.

Evidence gap: Non-human evidence. Broad claims about immunity, cancer and ageing derived from this literature are not established in people.

Melatonin adds to the effects of sedatives and alcohol, and several medicines change how quickly it is cleared. It may also affect blood pressure and glucose control in some people.

Short-term use in adults is usually well tolerated, with drowsiness, headache, dizziness, vivid dreams and next-morning grogginess most common. It is a hormone, and effects of long-term use, including during puberty, are not well characterised. Accidental ingestion by young children has increased sharply where gummies are common, and overdose has led to hospital admissions — store it out of reach and treat suspected ingestion as an emergency. Use in children should be clinician-directed. Avoid driving or operating machinery after taking it, and avoid in pregnancy and breastfeeding without advice. Persistent insomnia deserves assessment for causes such as sleep apnoea, pain or depression.

Tablets, liquids, gummies and prolonged-release products are available. Circadian uses depend on taking it at a specific time relative to the target sleep period rather than on taking more.

Cognitive behavioural therapy for insomnia is the first-line treatment for chronic insomnia, alongside consistent sleep timing, light exposure management, caffeine and alcohol review, and assessment for sleep apnoea. Melatonin fits best as a circadian tool rather than a sedative.

Educational example: a household keeps melatonin gummies on a kitchen counter and a young child eats several, leading to an emergency department visit. Another example: an adult takes melatonin at midnight for delayed sleep phase and finds it unhelpful because the timing is wrong. Decision factors are child-safe storage, correct timing, product content accuracy and whether the sleep problem has an untreated cause. Questions to ask: what time should I take it, does it interact with my medicines, and is this product independently tested? Marketing melatonin to children as a routine sleep aid outpaces the evidence.