There are many published studies on the benefits of mindfulness, here are some starting points:

How meditation changes the brain and body
How mindfulness improves health
Meditation could protect the brain from signs of ageing
Effects on depression / anxiety and pain using meditation
Meditation programs for stress and well-being
Relieves pain more effectively than a placebo
Effective treatment for insomnia
Changing gene expression with meditation
Huffington Post guide to benefits of meditation
Boosting productivity with mindfulness
Mindfulness training for military
Meditation & ageing
Reduces anxiety, depression and pain
The science of mindlessness and mindfulness