I suffer w/stiff neck myself. I have TOS and cervical disk and joint issues. I have found that sleeping on my back using a Tempurpedic pillow is finally possible now that I figured out that I have to have my lower legs elevated on a wedge and pillow. When sleeping on either side arms get numb and my neck is worse. The solution of back sleeping works for me but I had to have a PT work with me to make sure I got the right pillow height and shape for my needs. I also place a verticle roll of bubble wrap between the shoulder blades (designed by Dr Newkirk). The stiff necks aren't gone but it helps. I hope you can experiment to find something that helps you.