A bed pillow is made of elastic foam material. The pillow's top surface extends along both a longitudinal direction and a lateral direction that are mutually perpendicular, follows a top undulating pattern in the longitudinal direction, and is uniform in the lateral direction. The pillow's bottom surface is opposite the top surface, follows a bottom undulating pattern in the longitudinal direction, and is uniform in the lateral direction. The pillow's front surface and a rear surface extend from the top surface to the bottom surface, and are uniform in the lateral direction. The pillow has two laterally-opposite parallel planar side surfaces that extend from the top surface to the bottom surface and extend from the front surface to the rear surface.