Reciprocity versus rhythmicity in spontaneous alternations of nasal airflow

Active anterior rhinomanometry was used to observe nasal airflow in five men and four women (ages 18-30). Measurements were obtained for each nasal passage every 5 min throughout an uninterrupted 8-hr session. Facial skin temperature from the left and right side of the face was recorded simultaneously from thermocouples. Observations were made during the months of May and June; subjects were allowed to maintain their routine diurnally active schedules prior to observation. Airflow in the two passages showed a significant negative correlation (i.e. was reciprocal) in 44% of subjects (N = 9). Autocorrelation and spectral analysis of the airflow data found evidence of periodicity in 39% of individual nostrils and 56% of subjects. Mean estimated period was 4.5 +/- 1.0 hr (range 3.5-6.0 hr). Only 22% of subjects showed statistical evidence of periodicity in both nostrils (i.e. a "nasal cycle"). Left- and right-side facial skin temperatures changed in parallel rather than reciprocally, but showed evidence of periodicity in 50% of hemifacial time series (56% of subjects), with an estimated period of 3.8 +/- 1.0 hr (range 2.3-5.0).