Straightening of the physiological curvature of the cervical spine requires the selection of a suitable pillow for correction. Generally, the pillow should be one fist high for supine sleepers and one and a half fist high for lateral sleepers, about 10 cm, not too high. The pillow core should be filled with the right amount of filling to maintain a certain level of firmness and elasticity. A pillow with too much elasticity is likely to cause fatigue and injury to the neck muscles.