Measuring and Characterizing the Human Nasal Cycle.
Level 4 - case-series / case-control
Prospective observational physiological study in a single healthy cohort without a control group
PubMed 27711189 · doi:10.1371/journal.pone.0162918
What was done
The authors developed a low-cost tool for continuous, independent measurement of airflow in each nostril and tested it in 33 healthy right-handed subjects during 24-hour continuous recordings to statistically characterize nasal cycle dynamics across wake, sleep, and postural shifts.
What was found
Subjects spent slightly longer in left over right nostril dominance (left = 2.63 ± 0.89 hours, right = 2.17 ± 0.89 hours, t(32) = 2.07, p < 0.05). Cycle duration was shorter during wakefulness than during sleep (wake = 2.02 ± 1.7 hours, sleep = 4.5 ± 1.7 hours, t(30) = 5.73, p < 0.0001). Slower breathing was associated with a greater difference in flow across nostrils (r = 0.4, p < 0.0001). Lying on one side was associated with greater flow in the contralateral nostril (p < 0.002). Evidence was also found for airflow cycling within each individual nostril alone.
Why it matters
This paper introduces an accessible, low-cost methodology for continuous 24-hour nasal airflow monitoring and establishes baseline quantitative dynamics of the nasal cycle across physiological states.
Limits
The study was small (n = 33) and exclusively tested healthy right-handed individuals, preventing generalization to left-handed persons or clinical populations with structural nasal pathology or autonomic dysfunction. Potential diagnostic utility in disease was hypothesized but not directly tested.