OXYGEN - Lara Setiawati & Johnny B.A.N.G. Reilly (Short Film)

When we're stressed, hormones like cortisol flood our systems, producing the "fight or flight response" in which our heart rate goes up, we breathe more heavily (requiring more oxygen) and our blood vessels constrict. Breathing exercises -- or even just taking a few deep breaths -- can help reduce tension and relieve stress, thanks to an extra boost of oxygen. While shallow breathing -- a marker of stress -- stimulates the sympathetic nervous system, deep breathing does the opposite: It stimulates the parasympathetic reaction, which helps us to calm down.