Our sleeping position effects our facial symmetry and lines. Sleeping on the back is the best choice for symmetry and for avoiding the effects of compressing the skin on a pillow.
If you would like to sleep on your back, but have trouble getting or staying comfortable in the position, try tucking a pillow under the knees and also hugging another across the chest. The pillows can help to keep us in this position.
I, however, cannot sleep on my back and instead head to the left or right side. Symmetry is a bust, but I attempt to crease my face less by positioning my head on the pillow in a way that keeps my face free and clear from the pillow.
For women, note that sleeping on our side also compress the décolleté. Wrap your arms around a wide pillow to reduce compression in this area.