A body scan meditation, a component of Mindfulness-Based Stress Reduction, produces distinct immediate physiological effects compared to other relaxing activities. In two laboratory studies, healthy young adults showed greater increases in respiratory sinus arrhythmia (a measure of cardiac parasympathetic activity) during meditation than during progressive muscular relaxation or listening to a novel. Meditation also shortened the cardiac pre-ejection period, indicating increased sympathetic activity. These opposing autonomic changes may explain why heart rate did not change. Women experienced a larger drop in diastolic blood pressure during meditation, while men showed a greater increase in cardiac output. The findings suggest that body scan meditation triggers a unique combination of parasympathetic and sympathetic responses.
A systematic review and meta-analysis of 38 randomized controlled trials found low-quality evidence that mindfulness meditation is associated with a small decrease in pain compared with various control conditions in adults with chronic pain. Statistically significant improvements were also seen for depression symptoms and quality of life. Only seven of the included trials reported on safety. The authors conclude that while mindfulness meditation improves pain, depression, and quality of life, additional well-designed, large-scale trials are needed to provide more definitive estimates of its efficacy.