In some embodiments, a pillow including a viscoelastic sleeve defining a cavity and filler material positioned within the cavity is disclosed. In other embodiments the pillow includes a sleeve in which is received viscoelastic filler material, or includes a viscoelastic sleeve in which is received other type(s) of filler material.

Some embodiments of the disclosed pillows have a sleeve of viscoelastic material within which is received and enclosed a plurality of loose pieces of filler material. The sleeve can have one or more openings shaped and dimensioned to provide ventilation for the interior of the pillow and/or to enable a user to insert and remove an inner sleeve within which the filler material is retained. In some embodiments, the inner sleeve has two or more compartments for holding the same or different filler materials having the same or different densities, thereby providing a pillow adapted for different uses and support characteristics.