Down: Garnet Hill Insuloft side-sleeper pillow (top), $95, 800-622-6216. This pillow's baffled side panels provide the even sleeping surface needed to support your neck. Its 100 percent white-goose-down filler is specially cleaned to remove impurities, making it hypoallergenic. Pros: Long lifetime. Cons: Big initial investment.

Alternative: Natural Balance pillow (middle), $30, www.natureworksfibers.com for store locations. Introduced in February, NatureWorks is a synthetic fiber derived from corn. This fill has a high loft, which provides ample support for the neck and head. Pros: Made from a renewable resource; machine-wash and-dry, hypoallergenic; wicks away moisture. Cons: Not as soft or lofty as down.

Synthetic: PrimaLoft side-sleeper pillow (bottom), $39, www.landsend.com or 800-356-4444. PrimaLoft's clusters most closely imitate the loft and comfort of down, making it a wonderful alternative for the allergen-sensitive on a budget. Two-inch baffled side panels offer the neck support needed by side sleepers. Pros: Machine-wash and -dry; hypoallergenic. Cons:Synthetics don't last as long as natural fibers.