Do you have a significant other that could tell you? If not the video recorder is a good idea. If you don't have one with night vision see if you can borrow one for the evening. That way the room is still dark and you will be able to sleep, but the camera can still tape.
As for determining if you have SA, it sounds like your doc has an economically sound approach for you. You might see if you can borrow or rent an auto for a week before you buy (if the pricing isn't too bad) but worse case if the auto says you don't have it, you should be able to find someone willing to buy it.