Hoffstein and coworkers did not find differences in the mean or highest sound intensity across the sleep stages in heavy snorers. However, Nakano and coworkers reported increased snoring time and intensity during slow-wave sleep, when compared to REM sleep in apneic snorers. In the present study, the snoring intensity index was also found to be significantly higher during NREM sleep than during REM sleep in both sleep studies. Snoring seems more prevalent and more intense during stages 2 to 4 of NREM sleep. Since REM sleep is more prevalent in the early morning and sleep onset is followed by stages of NREM sleep, increased intensity of snoring during NREM sleep may have social implications. further
Previous studies have shown moderate decreases or no significant changes in nocturnal breathing disorders after treatment of nasal obstruction. Kiely and coworkers reported a significant decrease in AHI after intranasal corticosteroid therapy in a randomized placebo-controlled study of patients with symptoms of rhinitis. Variation in treatment outcome was noted, as was the case in other studies, but the change in apneic activity was correlated with the change in nasal resistance. Verse and coworkers followed snoring patients after nasal surgery for more than a year on average without improvement in SDB in the whole patient group, but they found a significant decrease in the number of arousals and improvement of daytime sleepiness as determined by ESS score. Improvements in sleep architecture (eg, increase in REM sleep) have been observed after treatment of severe nasal obstruction. Subjective improvement of sleep quality and daytime somnolence is frequently reported, although controlled studies of treatment outcome in nasal pathology are few. We found no improvement in nocturnal breathing, number of arousals, or ESS score in these patients despite an improvement in nasal resistance. This is probably mainly due to the large variety of influencing factors in an unselected clinical sample.