I often had the same performance anxieties that kept me up at least the night before a show. The more often I played helped it become less as a routine was established, but in slower times it builds again. Playing (out) regularly builds your confidence that overrides the anxiety. When I slowed down and considered stopping, which I did, I experienced the stresses again which actually contributed to my decision to quit performing.
I believe it is also related to personality traits. I've known some narcissistic performers who dont have this problem. Their ego just doesn't allow it. Though this ironically helps them succeed, I'm glad I am not one of them.