Molecular Mechanisms of Melatonin Action: Targets in Sleep Regulation

Melatonin, the principal hormone secreted by the pineal gland, influences the function of diverse neuroendocrine and other systems in mammals. This indoleamine hormone is also involved in maintaining brain homeostasis, entraining biological rhythms and coordinating reproductive function to changes in photoperiod in seasonal breeders.1,2 Other studies indicate a potentially important immunomodulatory role for melatonin which binds with high-affinity to T lymphocytes3 and is synthesized by human lymphocytes4