Summarize this article in one sentence.
You can find wedge pillows online, at drugstores, and at medical supply stores. On average, they cost around $40 (U.S.). If you suffer from acid reflux, you can also find wedges with arm inserts to promote a comfortable side sleeping position. Sleeping elevated on the left side is recommended to ease the symptoms of reflux disease. Stacking ordinary pillows isn’t an effective way to treat sleep apnea or acid reflux. It can actually worsen your symptoms by placing your body in an unnatural position. Further, it can cause neck pain and spinal misalignment. It’s best to use a wedge or elevate the entire bed in order to ensure the head, neck, and chest are all elevated properly. Bed wedges are foam inserts that fit between the mattress and box spring. At $50 to $100 (U.S.), they’re more expensive than most wedge pillows. Some people prefer them because they elevate the entire end of the mattress and reduce the chances of slipping down in the middle of the night, which is a common complaint of wedge pillow users. You can purchase multiple three inch wedges to gradually increase your mattress elevation so you can get used to the additional height. Aside from getting an adjustable bed, a mattress overlay is your most expensive option. You might prefer an inflatable overlay if you don’t like the look of a permanently elevated bed. You can deflate the pad during the day so the bed appears normal. Sliding down the bed is a common complaint, particularly among users of wedge pillows. Placing one or more large pillows at the foot of the bed will help you stay elevated and prevent overnight sliding. If you’re having sliding problems, you can also try swapping silk or satin sheets for a less slippery material, like flannel.

Summary:
Purchase a wedge pillow. Avoid just using piles of pillows. Buy a bed wedge to place under the mattress. Invest in an inflatable mattress pad. Place a large pillow at the foot of the bed to prevent sliding.