Mélatonine, rythme veille-sommeil et sommeil

Melatonin, a methoxyindole hormone secreted by the pineal gland, is synthesized at night under normal environmental conditions. The endogenous rhythm of secretion is generated by the suprachiasmatic nuclei and entrained to the light/dark cycle. Light is also able to suppress melatonin production according to the light schedule. Melatonin plays the role of an endogenous synchroniser, able to stabilize or to reinforce the rhythms such as core temperature and sleep-wake cycles. Exogenous melatonin is able to influence the endogenous secretion of the hormone according to a phase response curve. There are practical implications for this property in situations where biological rhythms are disturbed (jet-lag, delayed sleep phase syndrome, blind people, insomnia in elderly people). More clinical trials are needed to clarify the therapeutic interest of this compound.