The scary thing about sleep studies (From what I heard) is that it is rare when someone who takes one in their 40's or older passes with flying colors. True?
Note that the FAA is going to start making pilots submit to sleep apnea screening based on BMI in the near future.
http://www.avweb.com/avwebflash/news/FAA-Targets-Fat-Pilots-And-Controllers220978-1.html