This article was first published in Health magazine, March 2007.

Despite more offerings than a Swedish smorgasbord, beds boil down to four types: innerspring, foam, air, and water. The rest is gravy—more or fewer coils, more or less cushioning, multiple names for almost identical products, and prices that range from the hundreds to thousands. Toppers (foam, or just fluffy) are also being touted as a way to help rejuvenate an aging mattress. Here's a handy cheat sheet.

Most beds—80%—are innerspring, or coil. The number of coils varies from 250 to more than 1,000, and more coils add to durability and support. Thinner coils mean a softer nestle. Coil shape matters, too. Hourglass types compress over time, so your mattress gets harder. Continuous coils, wound from one wire, are thicker than others and offer a bit more buttressing. Pocket springs are in individual fabric compartments unconnected to the other springs. All of the coils hold layers of cushioning from cotton to cashmere. Popular brands include Serta Perfect Sleeper, Sealy Posturepedic, Simmons Beautyrest, and Therapedic Innergy.

A rising competitor is the memory-foam bed, which responds to the body's heat and weight, molding each sleeper into comfort. NASA invented viscoelastic foam in the 1970s to cushion astronauts' seats in flight. "Latex foam is also one hot category," says David Perry, executive editor and mattress writer for Furniture Today. "It has a natural antimicrobial nature." Tempur-Pedic is a widely publicized foam mattress, but others have entered the fray since then, including Serta Luxury Response Alternative Sleep Collection and Pure Response Latex Collection, TrueForm by Sealy Posturepedic, Verlo, Coverest, and Therapedic MemoryTouch.

Air and water
Air-mattress sales are ballooning, too. Sleepers can adjust the amount of air—and hence the firmness—in the whole bed or on one side only. Women who gain or lose weight (during pregnancy, for example) can add or release more air until they feel comfortable. And their partners can choose their own comfort level, as well. Major brands include Select Comfort's Sleep Number bed, AeroBed, and Therapedic AirTouch.

Water beds, around since tie-dye days, have a new twist too. Some have washable pillow tops along with, of course, all that water. Brands include FloCore by FloBeds and Land and Sky.