A sleep study can take a lot of time before it can be completed. If you usually sleep about 10 hours at night, expect that you are going to take that test for a long time. It is best that you know what to expect when you get there. You will be required to fill up some documents that will provide the information that the medical professionals need to know.
You will change into clothes that you know you can sleep in easily. It will take about 1 - 2 weeks before you can completely get the results of your test. There are some people who get their tests interpreted faster because of an emergency.