Sleeping position is a key factor in choosing the best pillow for body alignment and comfort. Fortunately for consumers, many pillows are labeled for specific sleeping positions.
Using a pillow while sleeping on your back
When lying on your back, the pillow should support the natural curve of the spine, with adequate support under the head, neck and shoulders. The height of the pillow should be lower than for side sleepers.
Placing another pillow or two under the knees further relieves back strain. Pillows tend to flatten the lumbar curve, relieving pressure on the facet joints in the back of the spine.
This position is the best overall for helping the back rest comfortably, and many people find that it’s the only way they can sleep during a bad attack of back pain or while recovering from spinal surgery.
Using a pillow while sleeping on your side
When lying on your side, the pillow should support your head and neck so that your spine maintains a straight and natural horizontal line. Sleeping on your side requires a thicker pillow than sleeping on your back.
Bending the knees and placing another pillow between the knees keeps the spine in a neutral position. When there is no support between the legs, the upper leg rotates downward, pulling on the pelvis and distorting the natural line of the spine. A firm pillow between the knees usually prevents this downward rotation better than a softer pillow.
Adding support between the knees can prevent back pain and allow your back to heal and rest better while you sleep.
There is limited research on side sleeper pillows. One small study found that a latex pillow was the most beneficial of the five types considered (foam, regular foam, polyester, feather, and standard latex).
Using a pillow while sleeping on your stomach
Sleeping on your stomach is the most stressful position for your back and neck. Doctors may advise patients to avoid stomach sleeping if they have certain spinal conditions or after spinal surgery.
If sleeping or resting on the stomach is preferred, the pillow should be relatively flat or the head should lie directly on the mattress so that the head and neck are not strained. In this position, it is often best to place another relatively flat pillow under the abdomen or pelvis to keep the lower back in a natural position.
Pillows for combined sleepers
Individuals with different sleeping positions should look for a pillow that has more side sleeping areas and lower back sleeping areas. A pillow with a mixture of different fillings or a buckwheat husk pillow can also be helpful. Using one multipurpose pillow will likely result in the pillow being too high for back sleepers and too low for side sleepers.