Testing before surgury/to get insurance approval.

Hi, I'm still in the process of all the tests pre-op. I have visited the nutritionist, the pulmunary doctor and am visiting the psych doctor today, the pulmunary doc again today for a breathing test and to see my surgeon, all on the same day. My pulmunary doctor has informed me that I need to do a sleep study and that my insurance will not cover the machine that I can bring home, so I will have to go to a local sleep center. My question is; what does this study entail? Do they strap me up? Do they give me something to make me sleep? Also; what other tests will be coming down the road for me? I am making all positive life changing choices for myself..quit smoking, stop my glass of wine daily to prepare for my surgury and my healthy life to come and I'm very excited. Thank you for your comments.