There is one aspect of health that is so commonplace that it is hardly ever consciously noticed - which is precisely why it is so often underestimated: breathing. Of course you know that fresh air is good for you. That hiking in the mountains or by the sea is good for you. But the crucial question is not which air you breathe in - but how you breathe in the first place. And even more specifically: Do you breathe through your nose or through your mouth? This one question - as simple as it sounds - has far-reaching consequences for your entire organism, for your nervous system, your immune system, your sleep, your emotional state and even your self-esteem.