Reversal of nostril dominance by posture.

Reflex reversal of differential air flow through nostrils (DAFTN) by the adoption of suitable lateral recumbent position was studied in male Nigerian subjects. The subjects who demonstrated more air flow through the left nostril initially in the supine position, adopted left lateral recumbent (LLR) position which brought the decongested left nostril to the down-side and the congested right nostril to the upside. Within 3 to 4 minutes after the adoption of LLR position, the air flow through the nostrils was equalised and by 11th minute the DAFTN was reversed, with more air flowing through the upsided right nostril. Return of the subjects to supine position could not result in the recovery to the initial pattern of DAFTN. It is suggested that reversal of DAFTN with adoption of suitable lateral recumbent position was a reflex effect due to the pressure stimuli to the lower lateral side of the body particularly around the shoulder region and effect was mediated through the sympathetic innervation to mucosal venous sinuses of the nostrils. Possibility of gravitational effect was ruled out.