One’s sleep position will dictate how a traditional mattress top pillow can be used to provide the appropriate support.
Using a pillow while sleeping on the back
When lying on the back, a pillow should support the natural curvature of the cervical spine, with adequate support under the head, neck, and shoulders.
When sleeping on the back, the height of the pillow should be lower than in the sideways position. Placing a pillow or two beneath the knees further alleviates any back strain, and is the gentlest position on the back.
Using a pillow while sleeping on the side
When lying on one’s side, a pillow should support the head and neck such that the spine maintains a straight and natural horizontal line. Weight should be evenly distributed so as not to create unnatural bending or pressure.