One is to meet the physiological needs: when supine, pillow can maintain the curvature of the neck, the edge of the pillow should remain curved, can not be slope-shaped; pillow height to meet the individual shoulder width, supine pillow height about a boxing, lying on the pillow should be one punch plus two fingers.
Two heights: Modern research has suggested that pillows are slightly lower than the shoulder to the same neck distance is advisable. Pillow height is based on the human neck 7 of the physiological curve of the cervical spine, only to adapt to this physiological bending, can make the shoulder and neck muscles, ligaments and joints in a relaxed state, pillows too high and too low are not conducive to human health.
Three length width: pillow to a slightly longer appropriate, the length of the pillow should be enough sleep to turn a position behind. Pillows are not too wide, too wide over the head and neck joints, muscle easily tense, to 15~20cm appropriate.
Four soft hardness: pillow with soft hardness moderate, slightly elastic for good. Pillow is too hard, head and neck contact with the relative pressure increases, causing discomfort; the pillow is too soft, it is difficult to maintain the normal height, so that the head and neck can not be supported by a certain fatigue; the pillow is too elastic, the brain is constantly affected by external elasticity, prone to muscle fatigue and damage.