Alternating dominance of cerebral hemispheric activity was demonstrated in humans by use of the electroencephalogram (EEG). Relative changes of electrocortical activity have a direct correlation with changes in the relative nostril dominance, the so-called nasal cycle. The nasal cycle is a phenomenon where efficiency of breathing alternates predominantly through right or left nostril with a periodicity ranging from 25 to greater than 200 minutes. Relatively greater integrated EEG value in one hemisphere correlates with predominant airflow in the contralateral nostril, defining a new interrelationship between cerebral dominance and peripheral autonomic nervous function.