Cut wood blocks 6 to 8 inches square with a saw. Place them under the feet at the head of your bed to raise the bed on an incline. If your bed has three legs across the head, place blocks under all three legs. If your bed frame has center supports, insert blocks that measure 3 to 4 inches square under the feet that support the center of the bed.
Purchase bed risers at a home goods store if you don't want to make your own. Packaged risers are a bit more expensive, but you can stack them to raise the height of your incline from 3 to 8 inches.
Buy a medium-firm upholstery foam sheet, although it's the most expensive solution. Foam sheets come in different thicknesses and can be cut to raise the head of your mattress. Place the foam between the box springs and the mattress, placing your bed on an incline.