I've had a couple of 9 hour sessions and never passed out.. I'd read or even kind of doze off a bit. Then my roomate decided to come with me for a tattoo when we moved to Montreal and no sooner did the needle touch his arm did he turn absolutely green. I started cracking up and the tattoo artist stopped and asked him if he needed a moment or something to eat. Now this is a guy that feels zero pain and is a complete maniac, but for some reason this just totally affected him and I honestly thought he'd faint. About 30 minutes in the color came back to his face and he was fine, but it was a good laugh at first.