How to prevent the adrenaline dump from happening?

Had my first BJJ competition yesterday and ended up coming 2nd in overtime because in the final my body just gave out and felt so heavy, I had many chances to submit my opponent but just didn't have the strength to keep hold of locks.

How do you prevent yourself from crashing like that? I know experience makes a big difference but is there anything that experienced competitors do that makes a difference?

Many Thanks.