Every type of side sleeper needs a thicker body pillow, but sleepers who prefer the yearner and fetal positions might need different shapes. Fetal position sleepers can put the same length of the pillow between their knees that they put between their arms because they bend their knees, so they might want a U-shape or rectangular shape. Yearners keep their arms out and their knees straight, so a C-shape might be better for them because the curve will go between their straightened legs.