Science on Yoga & Breath

Yoga is a combo of both breathing exercises - physical exercises - knowledge about the mind and body. 

You may Google on your own, but here is a collection for you...
Study shows how slow breathing induces tranquility (Stanford Medicine)
Why Breathing is so effective at reducing stress (Harvard Business Review)
Effect of yoga respiratory practice (Bhastrika pranayama) on anxiety, affect, and brain functional connectivity (Frontiers Media)
Immediate effect of slow pace bhasrika pranayama on blood pressure and heart rate (NIH - USA)
The science of breathing (Yoga Journal)
YOGA for health - What science says (NIH - USA)
16 benefits of yoga tha are supported by science (Healtline -artikkel)
Basic reseach (Yoga Alliance)