A condition that predominantly affects women, fibromyalgia is characterized by chronic pain and fatigue; common symptoms include muscle stiffness, sleep disturbances, gastrointestinal discomfort, anxiety and depression. Cortisol is a steroid hormone that is produced and released by the adrenal gland and functions as a component of the hypothalamic-pituitary-adrenal (HPA) axis in response to stress.  Previous research has found that women with fibromyalgia have lower-than-average cortisol levels, which contributs to pain, fatigue and stress sensitivity. Kathryn Curtis, from York University (Canada), and colleagues enrolled 22 subjects from the community to participate in a 75 minute yoga class twice weekly for 8 weeks. Questionnaires concerning pain, anxiety, depression, and mindfulness were administered pre-, mid- and post-intervention.  The team collected salivary cortisol samples three times a day for each of two days, pre- and post-intervention.  The researchers found that a program of 75 minutes of hatha yoga twice weekly over the course of eight weeks improved the subjects’ levels of mindfulness, whereby they were better able to detach from their psychological experience of pain. In concordance, the salivary cortisol samples revealed elevated levels of total cortisol, with the team positing that because hatha yoga promotes physical relaxation by decreasing activity of the sympathetic nervous system, thereby lowering heart rate and increases breath volume, the technique exerts a positive effect on the HPA axis.