['Fibromyalgia is a syndrome characterized by severe pain, fatigue and sleep disturbance. There is evidence of central hyper-responsiveness to sensory stimulation and impaired cardiovascular autonomic control. Laboratory investigations suggest that mindfulness-based stress reduction (MBSR) may improve autonomic functioning in fibromyalgia. However, these findings may not reflect what occurs during naturalistic conditions, and MBSR studies during real-life functioning are lacking. We conducted a randomized controlled, 3-armed study with 168 female FM patients. This report describes cardiac, respiratory and physical activity findings.', 'Eight-week MBSR was compared to wait-list and to active control intervention. Ambulatory accelerometry and cardiorespiratory function were monitored over 24-h periods at 3 time-points: pre- and post-intervention, and 8-week follow-up. Also baseline levels were compared with an age-matched group of 33 healthy women.', 'Activity, heart rate, respiratory sinus arrhythmia and ventilation were measured. Comparison with controls confirmed differences in cardiac autonomic tone and activity pattern among patients. Most measures also showed effects of time-of-day and point of measurement. There were no effects of treatment. Additionally, there were no relations between patient-reported clinical improvement and objective physiological or accelerometry parameters. Intervention-related benefits in wellbeing were not associated with changes in daytime cardiorespiratory measures or pattern of physical activity.'] Does mindfulness-based Intervention Influence Cardiac Autonomic Control or Pattern of Physical Activity in Fibromyalgia During Daily Life : An Ambulatory , Multi-measure Randomized Controlled Trial?