"Sleeping on your stomach forces your lower back into extension, and this jams your facets and shortens your muscles.
It also puts unnecssary strain on your neck as pillows tend to be quite a bit higher than the mattress.
The neck gets forced into extension even more so than the lower back, which could leave you with a crimp in your neck when you wake up in the morning.
To avoid these problems, we recommend sleeping on your side with appropriate support, or sleeping on your back with minimal pillow height. "
what is TDS?