There can be a few avenues for Science to analyse and postulate the mechanics of typical meditative responses, mostly focusing on physiological responses in the body. The hyper oxygenation of tissues is typically put forward to explain the many and varied sensations that manifest in breath type meditations. There is definitely truth to this line of thought.
On a mundane level, the breathing process is akin to physically massaging your organs and visceral body. From the membrane between your nose and brain, to the spaces between the convoluted tubes of your stomach and abdominal wall, breath reaches parts of you untouched by just about every other aspect of our lives and activates areas long laying dormant.
The power of touch has become very much become scientifically validated as essential for healthy human growth. Indeed as has the power of intention, the mental or “thought touch”, that we may consciously or otherwise “give” to another. For healings, prayer has been shown to be authentic as has group meditations.
There is a swath of studies being released every day now further asserting the wondrous ways that our bodies respond to breath, coupled with the devotional purity of our directed intention.