Sleep position is a key factor in choosing the best pillow for both body alignment and comfort. Fortunately for consumers, many pillows are labeled for specific sleep positions.
Using a Pillow While Sleeping on the Back
When lying on the back, a pillow should support the natural curvature, or lordosis, of the cervical spine, with adequate support under the head, neck, and shoulders. Pillow height should be lower than for side sleepers.
Placing another pillow or two beneath the knees further alleviates any back strain. The pillows tend to flatten the lumbar curve, easing the pressure on the facet joints in the back of the spinal column.
This position is the best overall to help the back rest comfortably, and many people find this is the only way they can sleep during a severe bout of back pain or while recovering from spine surgery.
Using a Pillow While Sleeping on the Side
When lying on one's side, a pillow should support the head and neck so the spine maintains a straight and natural horizontal line. A thicker pillow is needed for sleeping on the side than sleeping on the back.
Bending the knees and placing another pillow between the knees keeps the spine in the neutral position. When there is no support between the legs, the upper leg rotates downward, pulling 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 the back to heal and rest better while sleeping.
There is limited research on pillows for side sleepers. One small study found the latex pillow the most helpful of five types considered (foam contour-shaped, regular foam, polyester, feather, and standard latex. Study participants reported the most cervical stiffness upon waking after using feather pillows, with the symptoms continuing well into the day.1
Using a Pillow While Sleeping on the Stomach
Sleeping on the stomach is the most stressful position for the back and neck. Patients may be advised by their doctors to avoid sleeping on the stomach if they have certain spine conditions, or following spine surgery.
If sleeping or resting on the stomach is preferred, the pillow should be relatively flat, or the head should rest directly on the mattress, so the head and neck aren't strained. In this position, it is often best to place another relatively flat pillow under the abdomen or pelvis to help the lower back keep its natural alignment.
Pillows for Combination Sleepers
Individuals with varying sleep positions should look for a pillow that has higher areas for side sleeping and lower areas for back sleeping. A pillow with a mix of different fillers or a buckwheat hull pillow might be helpful as well. Using a single all-purpose pillow is likely to result in a pillow that is too high for sleeping on the back and too low for sleeping on the side.1