When I began using this pillow, my neck and shoulders were so tight that I could not look behind me to back the car out of our driveway, and I always slept on my stomach. It took a few nights to train myself to sleep in the appropriate positions for the pillow to do its job, but after that all was well.  My neck and shoulders had returned to their normal functioning, and I no longer had to think about sleeping in the position my orthopedist said is best for me given my particular needs -- on my side.  I have since gotten another of these pillows for my husband, and after a week he had stopped snoring.