The main role of a pillow during sleep is to support the cervical spine in a neutral position. This prevents adoption of more end-range cervical spine postures during sleep, which are believed to increase bio-mechanical stresses on cervical spine structures. A proper fitting cervical pillow can help you maintain the normal cervical curve while sleeping on your back, allowing your muscles and ligaments to relax and regain their normal length. This specialized pillow can also aid side sleepers by preventing unnatural bending in the neck.