Posture and Proper Breathing are both important to proper cognitive function. Proper breathing can help to regulate the Vagus Nerve, which has shown promise in treating depression, PTSD, and other mood/anxiety disorders. Below are studies detailing the effects proper posture and breathing/Vagus Nerve stimulation can have on cognitive function.
Vagal Nerve regulation is a critical factor in treating Depersonalization.
- Upright posture and mobility were associated with different cognitive processes, suggesting different underlying neural mechanisms. These results provide the first evidence for a link between postural
alignment and cognitive functioning in healthy older adults. These results are consistent with evidence that dopamine is important for memory and posture. Future studies will need to go beyond correlation to search for causal links between cognition and posture. 
- In summary, this is the first study to provide an indication that increasing postural demands contributes more to the observed increase in DLPFC activity during a postural dual-task than increasing the cognitive load. This suggests that changing the posture from normal stance to tandem stance increases cognitive load, at least in the DLPFC. 
- The vagus nerve is a major component of the autonomic nervous system, has an important role in the regulation of metabolic homeostasis, and plays a key role in the neuroendocrine-immune axis to maintain homeostasis through its afferent and efferent pathways. The relationship between depression, inflammation, metabolic syndrome, and heart disease might be mediated by the vagus nerve. VNS deserves further study for its potentially favorable effects on cardiovascular, cerebrovascular, metabolic, and other physiological biomarkers associated with depression morbidity and mortality. 
- The vagus nerve represents the main component of the parasympathetic nervous system, which oversees a vast array of crucial bodily functions, including control of mood, immune response, digestion, and heart rate. It establishes one of the connections between the brain and the
gastrointestinal tract and sends information about the state of the inner organs to the brain via afferent fibers.
- In this review article, we discuss various functions of the vagus nerve which make it an attractive target in treating psychiatric and gastrointestinal disorders. There is preliminary evidence that vagus nerve stimulation is a promising add-on treatment for treatment-refractory depression, posttraumatic stress disorder, and inflammatory bowel disease.
- The stimulation of vagal afferent fibers in the gut influences monoaminergic brain systems in the brain stem that play crucial roles in major psychiatric conditions, such as mood and anxiety disorders. Moreover, the vagus nerve plays an important role in the pathogenesis of psychiatric disorders, obesity as well as other stress-induced and inflammatory diseases.
- Because the vagus nerve sends information to brain regions important in the stress response (LC, orbitofrontal cortex, insula, hippocampus, and amygdala), this pathway might be involved in perceiving or manifesting various somatic and cognitive symptoms that characterize stress-related disorders. Since, the vagal tone is correlated with capacity to regulate stress responses and can be influenced by breathing, its increase through meditation and yoga likely contribute to resilience and the mitigation of mood and anxiety symptoms. 
- This new preclinical research shows that VNS bears the promise of being applied to a wider range of therapeutic applications. There is overwhelming evidence to suggest that vagus nerve is an important component of the immune response and manipulating vagal tone is a way to modulate the immune system. Using VNS to manipulate vagal tone provides an exciting new opportunity for minimally invasive therapeutic intervention in adult and pediatric patients. 
Breathing Through Your Nose:
- Recent research, stimulated by the growing awareness of the sleep apnea syndrome, has shown that nasal breathing plays a major role in the regulation of respiration in sleep. These observations are not new; they confirm century-old clinical findings on the importance of nasal breathing in sleep. 
- Individuals who habitually breathe through the mouth are more likely than nasal breathers to have sleep disorders and attention deficit hyperactive disorder. The hypothesis that mouth and nasal breathing give rise to different cerebral hemodynamic responses in the prefrontal cortex was corroborated in this study. We found that mouth breathing caused an increased oxygen load in the prefrontal cortex. 
- There is increasing interest in the fact that breathing exclusively through one nostril may alter the autonomic functions. These results suggest that breathing selectively through either nostril could have a marked activating effect or a relaxing effect on the sympathetic nervous system. The therapeutic implications of being able to alter metabolism by changing the breathing pattern have been mentioned. 
- Whereas modern brain imaging often demands holding body positions incongruent with everyday life, posture governs both neural activity and cognitive performance. Across numerous experiments, posture reliably influences brain data, core physiology, and cognitive performance.