Nasal resistance during wakefulness and sleep in normal man.

Previously, we reported an increase in supralaryngeal resistance during sleep in normal man. Since nasal resistance is known to fluctuate over a wide range of circumstances, we hypothesized that the increase in supralaryngeal resistance observed was due to an increase in nasal resistance. Therefore, the purpose of this investigation was to examine changes in total and unilateral nasal resistance in five normal, adult males during wakefulness, Stage 2 (non-REM) sleep and REM sleep. Transnasal pressure and flow were measured for each side of the nose. Resistance was calculated from the slope of the linear portion of the transnasal pressure-flow relationship. During wakefulness and sleep, resistance was substantially higher on one side of the nose or unilateral total occlusion was present. This high resistance fluctuated from side to side during sleep. The transition of high resistance from side-to-side occurred rapidly. On turning to either side, the side of the nose with the high resistance was not necessarily the gravitationally-dependent side. Total nasal resistance did not change significantly during sleep. We concluded that 1) resistance on one side of the nose is usually considerably higher than the other side, 2) this high resistance side alternates during sleep as well as wakefulness, 3) since this alteration occurs rapidly and is not dependent on gravity, reflexes are likely involved and 4) changes in total nasal resistance were not responsible for the increased supralaryngeal resistance we have observed during sleep.