Our moods are affected by our brain and our nervous system. Studies have shown that our nose is linked to the function of our amygdala, which contributes to our ability to feel emotions and perceive them in others, and our parasympathetic nervous system, which is associated with feelings of centeredness and relaxation. When we breathe through our nose, we activate our body’s ability to regulate physical and mental stress, and to maintain emotional balance.
Happiness looks good on you
Conversely, breathing through your mouth causes hyperventilation, which triggers the sympathetic nervous system and activates our fight-or-flight response. When this side of our nervous system is activated, our focus drops and our stress response goes up, contributing to feelings of anxiety and depression–despite the endorphins exercise can stimulate.
Read the study here: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3681046/