Hi, welcome to the forum, there are hormones
and neurotransmitters
and receptors which play role in
sleep and wakefulness. Melatonin is one such hormone and it appears to be the primary sleep-regulating hormone of the body. It is secreted in relation with normal day/night cycles. It affects sleep itself, decreasing sleep latency, increasing sleep efficiency, and increasing the total sleep time. Melatonin acts on the melatonin receptors.