Not on your stomach! Sleep on sides with a pillow that makes your spine and neck in a straight line (a small molded pillow). Put a small pillow between your knees so your hips are aligned. If you sleep on your back, put a medium pillow under your knees to relieve the lower back. Make sure your mattress is firm -- not soft.
I've had neck & lower back surgery (May on my back) I slept just fine in my bed right after surgery. I agree, sides & back & use the pillows!! I used them before& probably always will. Don't sleep on your stomach. There are times I can't get comfortable in my bed and I can in my chair. I've got to have sleep, so I do sleep in my lounge chair. Good luck on your surgery!!