Side sleepers may need a firmer, thicker pillow. Experts recommend you look for one that’s as thick as the distance between your ear and outside shoulder. Stomach sleepers often prefer a soft pillow underneath their head. A pillow under your stomach and pelvis may help prevent back pain. Back sleepers may need a soft, flatter pillow, to keep your head and neck in alignment. If you have neck pain and sleep on your back, look for a pillow that provides additional support, while maintaining the softness that’s comfortable for you.