Allergies was asked to provide a scientific opinion on a list of health claims pursuant to Article 13 of Regulation (EC) No 1924/2006. This opinion addresses the scientific substantiation of a health claim in relation to melatonin and reduction of sleep onset latency. The scientific substantiation is based on the information provided by the Member States in the consolidated list of Article 13 health claims and references that EFSA has received from Member States or directly from stakeholders. The food constituent that is the subject of the health claim is melatonin. The Panel considers that melatonin is sufficiently characterised. The claimed effects are “sleep-wake cycle regulation”, “relaxation” and “sleep patterns”. The target population is assumed to be the general population. In the context of the proposed wordings and the clarifications from Member States and the references provided, the Panel assumes that the claimed effects refer to the reduction of sleep onset latency (time taken to fall asleep). The Panel considers that reduction of sleep onset latency might be a beneficial physiological effect. In weighing the evidence, the Panel took into account that a meta-analysis of controlled human intervention studies in normal sleepers indicated a statistically significant reduction of sleep onset latency following melatonin consumption, and that these results were supported by two meta-analyses of controlled human intervention studies, one in subjects with primary sleep disorders and one in healthy subjects combined with subjects with insomnia. On the basis of the data presented, the Panel concludes that a cause and effect relationship has been established between the consumption of melatonin and reduction of sleep onset latency. The Panel considers that in order to obtain the claimed effect, 1 mg of melatonin should be consumed close to bedtime. The target population is the general population.