A small 2011 study in the Journal of Alternative and Complementary Medicine found that people were able to "subjectively relax" once they got used to the initial pain of sitting on the mat. Researchers didn't find any differences in participants' saliva cortisol levels (a marker that's often used to measure a person's stress response ) after using the mats, but they did say that lying on the mat was able to illicit a " parasympathetic response ." In other words, they seemed to be chilled out. There's not a whole lot you can gain from this one study alone, because there are too many variables that weren't taken into account (such as how stressed participants were before using the mats), and it could always just be a placebo effect.