There is a fabby article in New Scientist 8 January 2011, 'everybody say om':
showing how scientific studies support what yogis and meditators have known for years. That there are many measurable health benefits.
COGNITIVE- improved attention, sustained concentration & faster processing of working memory
HEALTH- reduces chronic pain,helps combat eating disorders, improves psoriasis, reduces depression, helps control substance abuse and slows cellular ageing
EMOTIONAL- reduces anxiety, helps combat stress, reduces impulse control and reduces emotional reactivity
BEHAVIOURAL- promotes acts of empathy and increases compassionate behaviour
Worth a read if you can get your hands on it.... a student kindly gave it to me.