So your doctor recommends you undergo overnight sleep study testing to assess for a sleep disorder like sleep apnea, but what should you expect? Polysomnograms are typically done in specialized sleep testing centers. Though you may have some anxiety about the experience, take a few moments, read on and lay those fears to rest. Discover the purpose of sleep testing, how to prepare before the visit, what to expect when you arrive, and how soon you will receive the interpretation of the results.