The Nasal Cycle During Wakefulness and Sleep and Its Relation to Body Position

Objectives/Hypothesis: To compare the occurrence, duration, and relative amplitudes of the nasal cycle (NC) during wakefulness and sleep, and to investigate the relationship of the NC to body position. Study Design/Methods: In 20 healthy subjects, the NC was measured by long-term rhinoflowmetry for an average 23.1 hours during wakefulness and sleep. Head and body position were also recorded during the night. Results: A classic NC was displayed by 50% of subjects during wakefulness and by 75% of the subjects during sleep. Cycle duration during wakefulness was 91.1 minutes (+/- 65.2; 20-337), increasing significantly during sleep to 178 minutes (+/- 92.8; 21-498) (P < 0.01). The relative mean flow of the working phase during wakefulness was 67.6% (+/- 8.0; 58-90), and it was significantly higher during sleep at 82.0% (+/- 6.8; 63-93) (P < 0.01). On recumbency, there was a significant correlation between body position and resting phase side (r=0.67; P=0.024). To a significant extent, positional shifts led to subsequent NC laterality changes (22%; P < 0.01). Conversely, to a significant extent, positional shifts preceded NC laterality changes (57.6%; P < 0.01). Body position changed in a nonsignificant number of cases (30.3%; P=0.16) due to reversal of the congestion side of the inferior turbinates. Conclusion: The results of our study show that the NC during sleep is characterized by longer cycle durations and greater amplitudes than during wakefulness on normal physical activity. Shifts in body position during sleep alter the NC in a specific direction to a significant extent, but the opposite is not the case.