CLOCK HORMONE. “One such link has been made with melatonin, a hormone produced by the pineal gland in a circadian manner to regulate sleep.”
https://www.nature.com/articles/s41591-018-0271-8?fbclid=IwAR01C2Z4J5lxVYDLhxIb9dPb3fhNSZSxwimZvhHaJ4n3-nVPpkt2PNqoukk