Melatonin

I'm just going to take on where we left off. The hormone I want to now talk about is called melatonin. The synthesis is in the pineal gland, which is very small. It is the size of a pea in your brain. Descartes called it the "seat of the soul," and it is where melatonin is made. It also has a rhythm. In a sense, it is the opposite of cortisol. It peaks at night. We call it the "darkness hormone." In every species that we have studied, melatonin occurs at night. It is a hormone that prepares you for the things that your species does at night. So, of course, in humans we sleep, but animals like rodents are awake. So, it is a hormone that is related to darkness behavior.