Influences of NREM sleep on activity of palatoglossus and levator palatini muscles in normal men.

Most evidence indicates that palatal position has an important influence on respiration during sleep. We have previously demonstrated during wakefulness that the levator palatini (LP) and the palatoglossus (PG) muscles function in an integrated manner in determining the route of respiration. In this study we first determined the effect of non-rapid-eye-movement (NREM) sleep on LP and PG electromyograms (EMGs) and then assessed if subjects could switch from nasal (NR) to oral (OR) respiration during NREM sleep without arousal. Six normal males subjects were studied using intramuscular EMG recording electrodes (LP and PG) and a divided mask to separate NR and OR. Peak inspiratory and end-expiratory EMGs of the LP fell significantly during NREM sleep [3.7 +/- 0.4 (SE), 1.9 +/- 0.4, and 2.4 +/- 0.7 arbitrary units for LP peak inspiratory awake, stage 2, and stage 3/4, respectively; 2.7 +/- 0.2, 1.5 +/- 0.2, and 1.8 +/- 0.5 arbitrary units for LP end-expiratory awake, stage 2, and stage 3/4, respectively; P < 0.05]. In a similar manner, the peak inspiratory EMG of the PG fell from wakefulness to stage 2 NREM sleep [5.1 +/- 0.5 and 3.9 +/- 0.5 arbitrary units for PG peak inspiratory awake and stage 2, respectively]. On the other hand, the PG peak inspiratory activity returned to near waking levels during stage 3/4 sleep, with the PG end-expiratory activity never falling during sleep. A total of 14 nasal occlusions were performed during NREM sleep. In all cases except one, an arousal was required to institute a change to OR.(ABSTRACT TRUNCATED AT 250 WORDS)