The position you sleep in may create stresses on structures (as discs, tendons or muscles). Sleep in the position that is most comfortable and best for your own relaxation, but one that will not contribute to pain or aggravate or perpetuate spinal problems.
Sleeping on your back.
Sleeping on your back is one of the least stressful positions and is usually recommended for proper spinal alignment. If you sleep on your back, avoid thick pillows under your head that can force the head forward and place constant stress on the upper back and neck. Over a period of time, this persistent forward pressure may affect the normal curvature of the upper back and neck, leading to possible spinal alignments and a wide range of health problems that may ensue. Patients who suffer chronic or even intermittent back pain may prefer to sleep on their back with a pillow under their knees. However, if you have a history of disc bulges in the lower back, especially the disc L5-S1, sleeping on the lower back may increase the pressure on the sacrum.
Sleeping on your side.
An alternate position is sleeping on your side with your knees bent. When you sleep on your side it is essential to use enough pillows to prop up your head so that it is level with the rest of your spinal column. You will need proper support under your head and a pillow thick enough to fill the gap between your head and shoulder. Try lying with your lower leg fairly straight and bend your upper leg.This position is usually suggested for those with low-back conditions and expectant mothers because it enhances relaxation, especially to the lower back. Pregnant women may find it helpful to place another pillow between the knees for maximum relaxation in this position.
Sleeping on your stomach.
Normally, it is recommended that you avoid sleeping on your stomach. If you do, your face is forced to turn to either the extreme right or left in order to breathe. This may cause undue stress in the joints of the cervical spine, as well as stretching and/or shortening of the muscles and ligaments on one side of the spine or the other. Stomach (prone) sleeping may also help cause the rib cage to shift due to the body weight on the chest, and may contribute to stress in the lower back, extending into the hips, legs and feet. Symptoms of stomach sleeping may include neck and shoulder stiffness, acute torticollis (wry neck), and morning headache. Changing a built-in habit is difficult but in some cases it makes all the difference.