how does cortisol work??

I'm interested in knowing how cortisol works. I have an 'anxiety'' cycle thats seems to follow the ''cortisol'' cycle. I'm anxious and nervous in the morning and into the afternoon. If I get out a bit and exercise, it gets better. And by evening time, the anxiety goes down.....AND.....by nightime its GONE...(8.00-12.00PM) This follows the cortisol cycle. Am I suffering from TOO much cortisol or NOT ENOUGH cortisol in my system? Please explain how cortisol works.......THANK'S GUYS... Tweet