One study of sleep positions reports that 41 percent of the participants sleep in the fetal position, on their sides, with their legs slightly bent and pulled toward the chest. Sleep specialists say side sleeping keeps airways open, reducing snoring and sleep apnea, providing more restful sleep.
The second most common side-sleeping position in the study includes the log, in which 15 percent of the participants' legs are straight and arms are at their sides. The third most common sleeping position ranked in the study is the yearner, in which 13 percent of the participants arms stretch straight out in front of their bodies. The least common positions are sleeping on the back and on the stomach, either of which may cause back and neck pain.