While it is usually comfortable to slumber in what is called the fetal position, with legs curled up, this could make for an uneven distribution of weight and produce back pain and sore joints. It may also bring on hip pain (hip bursitis) and shoulder pain, which include shoulder bursitis. https://www.theorthopaedicandpainpractice.com/the-best-sleeping-positions-to-relieve-neck-pain/