[praptak]

There seems to be quite a lot of research on this topic, see http://en.wikipedia.org/wiki/Research_on_meditation

This article: "Mindfulness-based stress reduction and health benefits. A meta-analysis" http://www.ncbi.nlm.nih.gov/pubmed/15256293 seems to be relevant to your question.

Of course the mere existence of articles does not prove anything. Caution advised :)

[zbuc]

MBSR is becoming increasingly common in cognitive behavioral therapy as well -- it's interesting (to me) to see how much intersection there is between meditative practice and what cognitive behavioral therapy is discovering. Different paths to the same conclusions.