Polyester is a man-made plastic and its fibers are utilized as pillow stuffing. The larger the thread count, the better the quality of filling. Pillows made with polyester stuffing are inexpensive and their durability allows usage of up to two years. Three-dimensional fiber clusters hold their shape for neck, head and shoulder support. Polyester stuffing tends to absorb sweat and facial oil more readily. It is necessary to clean the pillows regularly; however, they can be machine-washed. The filling is a synthetic material, making it free of odors and allergens.
Memory foam was developed in the 1970s by the NASA Ames Research Center to help reduce the g-forces on astronauts during lift-off. This same filling is now used in pillows to allow equal distribution of a person's weight during sleep. The foam conforms to the head and neck, returning to its previous shape once the pressure is removed. This visco-elasticity allows for easy adaptation to head movements during the night. Foam within the pillow has hundreds of holes that provide adequate air circulation and prevent moisture collection. Since bacteria and mildew cannot live in foam, the pillows are hypo-allergenic. Dust mites are three times less likely to survive on a foam pillow.
Down feather pillows offer a lightweight, softer way for side sleepers to feel comfort throughout the night. Down consists of the small feathers found underneath outer feathers on birds. Since down is smaller, it lacks the barbules that can poke out through a feather pillow. The fibers hold warm air close to a person's head and work as an insulator. Down pillows are durable and will retain their shape over time. Down is gathered from ducks and geese, but eider duck down is a preferred pillow stuffing. Cost fluctuates according to fill content and type of down. The pricier down pillows come from geese and the fill content is higher.