This will probably appear to be some rather bad advice... but last night i played after i had 4 pints of beer. I was relatively sedate. I played for probably 3 or 4 times longer than i normally play for, got through loads of incredibly scary parts, and really enjoyed all of it.
I found that I had a lot more courage this way and was a lot less tentative unless given a real strong reason to be. I got chased on two occasions, which were really terrifying. I was still getting scared and getting adrenalin rushes, but i seemed to have a higher tolerance to it and thus could keep going much longer.
I'll be doing this again no doubt.