Why Does Melatonin Rise Hours Before Sleep?

On the show, melatonin usually starts to rise as dusk approaches, hours before sleep. When the system is working in the correct way, melatonin is already on the march for some hours before sleep itself, and the rising peak usually arrives an hour or two later, around the time of sleep, though timing varies from person to person.

Light through the eyes normally acts like a hard brake pedal that stamps down and prevents the release and production of melatonin. Hunter-gatherer tribes untouched by electricity show the unlit pattern: as dusk approaches, the brake fades, the spigot of melatonin opens, and melatonin starts getting released. The rise continues, and the peak usually lands an hour or two later, around sleep.

Melatonin has usually already kicked in before the eyes shut.