Melatonin Circadian
Melatonin is a circadian rhythm regulator. Our circadian rhythm regulates the wake and sleep cycles, and every cell and organ in our body is affected by it, he said. Melatonin works to keep the circadian rhythm in sync.
Because it is extremely light-sensitive, melatonin will respond to exposure to morning light when signaled to our brain to pull back its release of melatonin. Morning light also signals the brain to release cortisol, our wakefulness hormone. Cortisol wakes us up and should be at its peak in the morning. Melatonin and cortisol are in an opposite relationship; when melatonin is high, cortisol should be low and vice versa. When the balance of any of these is disturbed, our sleep quality is also affected.