Is there any research-based evidence about how mindfulness affects our brains and reduces stress?

While people have reported personal experiences relating to the positive effects of mindfulness for thousands of year, it has only been recently that science has been able to use research to confirm and label its effects on the brain. Using a training technique called Mindfulness-Based Stress Reduction (MBSR), which has been widely reported as an effective approach for promoting psychological wellness, a group of scientists lead by Britta K Hölzel was able to measure the effects of mindfulness on the brain. 

The findings of their research showed changes in the brain including increases in gray matter, where the majority of the processing in the brain takes place, in many areas. The areas most affected by these changes were areas responsible for emotional regulation, learning and memory, perspective and self-referential processing, or how you see yourself and events in reference to yourself. In addition to this, Hölzel cites two other studies (one conducted by Hölzel and one from another scientist) that shows growth in the hippocampus. This is important because it means that damage done to the hippocampus from prolonged stress and some related psychological problems may be reversible through mindfulness.

Mindfulness and related practices such as meditation and even prayer have long been reported to have a positive impact on practitioner's mental well being. Quantitative research has been and is currently being done in an attempt to see if the reported psychological effects have a physical basis. With the advances in science, especially in brain imaging, scientists are now able to confirm links when they exist and promote these practices for general use when the evidence supports it.