Its an apnea test. When I was in the hospital for pancreatitis, I apparently stopped breathing for a while, my o2 dropped to 32%, and they called a code on me. I came to with like seven orderlies trying to tye me into restraints and me fighting the fuck out of them. Apparently when they started doing whatever they were doing to get my o2 back up I (completely unconsciously) started fighting them. They called security and everything who showed up after I sort of became conscious, but stood there for like 20 minutes with straps (not guns, I mean actual straps, like mental patient status straps). So anyway, apparently I have a sleep disorder, and my doc wants me to get tested, and I got excellent insurance now (thanks, Obama!) so fuck it. They wanted me to go in and do an in house sleep study, and I basically laughed in their faces and said unless they're providing me with a fifth of whiskey and bitch to suck my dick there was zero chance I was going to A) be able to sleep and B) be willing to try. They said 'oh everyone says that' and I said 'yeah breh, im sure they do, but the only thing thats gotten me to sleep anywhere but my own house in the past 15 years has included pussy and booze, and I aint your average bear.' and they left it at that.
tl;dr I stop breathing in my sleep.