Sleeping on your stomach may be second nature to some people, but apart from possibly easing snoring, there is little good to be said about this sleeping position. In fact, resting on the tummy at night is widely regarded as the very worst sleeping position.
Your spine has a natural curve, which is flattened out when laying on your front, placing a strain on your back and spine. This is because the middle of your body is where most of your weight is, making it difficult to maintain a neutral spine position whilst you are sleeping.
Stress on the spine increases stress throughout the rest of your frame. Since the spine is a pipeline for your nerves, spinal stress can cause pain just about anywhere in your body, including nasty headaches. You may also experience tingling and numbness, as if parts of you have “fallen asleep” (while the rest of you is uncomfortable and wide awake).
Additionally if you are sleeping on your stomach, unless you have somehow figured out how to breathe through your pillow, you will need to turn your head to the side while sleeping. This position will put your head and spine out of alignment, twisting your neck. You might not notice the damage this causes after one episode of stomach sleeping, but over time neck problems can become evident.