I don't know what kind of test it was or how it was done. Mine was in a sleep lab by a sleep specialist. They stuck about a zillion electrodes all over my head & body, which were plugged into monitors & stuff, and they had a camera & microphone on me all night. If I even whispered, the technicians could hear me and we could have a conversation.
http://en.wikipedia.org/wiki/Sleep_medicine

The dx was based on the number of times per hour I stopped breathing (I don't recall the exact criteria, but I do recall that it can vary with different labs/doctors), and analysis of the data collected from the electrodes/monitors. My apnea turned out to be fairly serious; I now require/use a c-pap machine & foam wedge.

Most (if not all) tests are fallible in one way or another. If it's (pardon the sick humor) keeping you up nights , it's up to you if it's worth pursuing.

Doc