Is there a right way to sleep ?
This question is difficult to answer because it is both patient, and injury/condition dependent. Regardless, we might be making this topic a little more complicated than it needs to be.
Prone (face down)
Sleeping prone (on your stomach) can aggravate certain conditions, or alleviate pain in others. For example, if you have an acute disc herniation or “disc bulge”, sleeping on your stomach might actually have some benefit due to the common aggravation of pain with flexion of the spine. On the other hand, if your pain is due to some sort of facet joint problem, neck issue, or upper back problem, sleeping prone may increase the discomfort.
Supine (face up)
Regardless of the condition, sleeping supine (on your back) is a pretty safe bet. Your spine is in a neutral position and there is no added stress to the soft tissues. Adding a small rolled up towel behind your neck may be an added benefit and restore the natural curve of the neck. I would also recommend a pillow under your knees to take some pressure off the low back.
Side sleeping is another good option for most conditions. There is no added stress to the joints of the spine or the soft tissues. If you are going to sleep on your side, pillow height is an important factor to take into account. We want the thickness of the pillow to be roughly the thickness of the space between the shoulder and the neck. A pillow too thick or too thin will cause our neck to be laterally flexed and could cause some temporary stiffness upon waking.
If you have found a certain sleeping position that allows you to be comfortable, get adequate rest, and wake up feeling ok, then great. If you are having issues such as neck and shoulder pain, back pain, or numbness in the arms or legs there is most likely an underlying problem. Try these tips and see if they help your pain. But more importantly, go get checked out by a health professional.