Question

Why human gone sleepy. How and by which hormone????????

Answer 1

Your body releases chemicals in a daily rhythm, which your body clock controls. When it gets dark, your body releases a hormone called melatonin (mel-ah-TONE-in). Melatonin signals your body that it's time to prepare for sleep, and it helps you feel drowsy.

Melatonin is a hormone produced in the pinealgland of the brain that is responsible for regulating sleep cycles.