Spine and Posture Basics
The spine is a column of 24 individual bones called vertebrae that support the body's weight and protect the spinal cord. Spinal disks, located between the vertebrae, hold the spine in shape and act as shock absorbers. The spine has three natural curves if viewed from the side of the body. These are the cervical (neck area) curve, the thoracic (upper back) curve and the lumbar (lower back) curve. These three curves give the spine an "S" shape when viewed from the side of the body. When viewed from the front or back of the body, a healthy spine forms a straight line.
Good posture refers to a body position that keeps the spine in the natural shape described above. Good posture reduces strain on the muscles and ligaments of the spine, and prevents muscular pain(9). Unfortunately, common sleeping positions often lead to poor sleeping posture and neck and back pain when sleeping(1,4,6,7).
Side Sleeping Posture
The side sleeping position is considered the most popular. In this sleep position, the spine maintains its natural S shape, which promotes good sleep posture. Normal side sleeping does have some disadvantages though. When the body is lying on its side, gravity pulls the spine from its naturally straight shape (when viewed from the front or back of the body). This can lead the neck and lower back regions of the spine to bend toward the sleep surface and cause neck or back pain when sleeping. Side sleeping may also result in lower back strain due to over-rotation of the pelvis.
The key to proper posture in this position is to keep the spine in a straight line (when viewed from the front or back of the body). Traditional head pillows can raise the head at excessive angles, but sleeping without a pillow typically results in a lack of support. To maintain the spines straight shape, a neck support pillow should support both the head and neck and position them parallel to the bed. To prevent strain in the lower back, a support pillow should be provided beneath the waist and under the upper leg. By positioning the spine in a straight shape and the legs parallel to each other, the body maintains good posture by raising the lower back into alignment and preventing excessive rotation of the pelvis(1,4,6,7).
Back Sleeping Posture
This sleep position is the second most popular as it is preferred by approximately 30% of people. The typical back sleeping position places strain on the lower back and neck. Normally, the buttocks and the upper back are in contact with the sleep surface, while the lower back is minimally supported. This posture can strain the lower back and cause pain and discomfort. Traditional pillows often provide minimal neck support and induce neck strain in this position.
To achieve better sleep posture, research studies and leading medical institutions recommend supporting the neck, lower back, and knees during back sleep. Placing a support pillow between the neck and sleep surface will maintain the cervical curve of the spine. Placing a support pillow under the lower back and knees reduces strain on the lumbar curve of the lower back. The use of a neck support pillow can improve support for the curvical curve of the spine. Altogether, these practices distribute the force of gravity across the length of the spine and reduce the probability neck or back pain during sleep(1,4,6,7).
Stomach Sleeping Posture
For adults, this sleep position places the greatest degree of stress on the spine. Perhaps for that reason, it is the least common. Stomach sleeping, especially on soft surfaces, forces the lumbar curve of the lower back into a flattened position. This is known to cause muscle strain and can lead to lower back pain. Stomach sleeping also forces rotation of the head which can result in strain to the neck. Medical professionals often encourage stomach sleepers to try to adopt another sleep position for these reasons.
People who prefer this sleep position can prevent muscle strain by making changes to their sleep posture. Placing a back support pillow under the pelvis will raise lower back and help maintain the lumbar curve. Individuals who experience neck discomfort should consider placing a pillow support under the shoulder on the side to which the head is turned - this will reduce the degree of head and neck rotation(1,4,6,7).