Patients often ask if they must sleep on their backs, for the sake of their necks, even though they are more comfortable on their sides. The answer is a qualified “No.”
It depends on the pillow you use under your head and neck. A pillow that adequately supports your cervical curve and maintains your spine in proper alignment is essential for healthy side sleeping.
I recommend an orthopedically designed pillow. I am a side sleeper, and this is what I use. I have orthopedic pillows in my office for my patients, and although the particular configuration may not be comfortable for a small percentage of patients, it works beautifully for most.
Side sleeping is OK if you have the right pillow.