Problem:
I'm wondering what produces the feeling of hunger in humans. Checking Wikipedia revealed that leptin and ghrelin are two hormones involved. I've also read that the digestive system produces its own melatonin.
Because melatonin is related to circadian rhythm and the biological clock,
Required:
Question 1: Is melatonin involved in feeling hungry?
Question 2: Is there a circadian pattern to the levels of leptin and ghrelin in humans?
Explain all the levels.