INFLUENCES OF NREM SLEEP ON ACTIVITY OF PALATOGLOSSUS AND LEVATOR PALATINI MUSCLES IN NORMAL MEN

Most evidence indicates that palatal position has an important influen ce 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 the n assessed if subjects could switch from nasal (NR) to oral (OR) respi ration during NREM sleep without arousal. Six normal males subjects we re studied using intramuscular EMG recording electrodes (LP and PG) an d a divided mask to separate NR and OR. Peak inspiratory and end-expir atory 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 inspir atory 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, st age 2, and stage 3/4, respectively; P < 0.05]. In a similar manner, th e 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 inspir atory 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 a ll cases except one, an arousal was required to institute a change to OR. We conclude 1) sleep appears to have a greater impact on LP EMG th an on PG EMG and 2) a change from NR to OR is rarely possible during N REM sleep in response to nasal occlusion.