Melatonin (N-acetyl-5-methoxytryptamin) is synthesized in the pineal body exclusively during periods of darkness. It plays an important role in initiating and maintaining sleep. In elderly people, concentrations of endogenous melatonin usually decline, and this is often associated with insomnia.1 Treatment with melatonin is effective in restoring normal sleep and improving quality of life in people over 55 years of age.1 Melatonin has also been used to treat children with developmental disabilities and sleep difficulties. It has been shown to be preferable to hypnotics, such as clonidine and benzodiazepines, because it does not affect sleep architecture or have adverse side effects.2 3 4

In a linked research paper (doi:10.1136/bmj.e6664) Gringras and colleagues randomised 146 children with neurodevelopmental delay and other diseases (epilepsy or autistic …