Melatonin is a neurohormone produced by the pineal gland that helps regulate sleep cycles. It is affected by the amount of daylight hours, because it is only released in the dark. Things such as the amount of time spent on the computer and watching TV can also affect how well and how much you sleep.
A small endocrine gland in the brain that produces melatonin; regulates seasonal functions and the timing of sleep cycles.
Feedback loops and homeostasis
The feedback loops help maintain homeostasis by making the body adjust to change. A negative feedback loop suppresses the original response. Controlling the amount of different chemicals in the body is released and keep the body functioning. A positive feedback loop tells the system to keep doing what it is doing.