Relationships between nasal obstruction, observed apnea, and daytime sleepiness

We administered a questionnaire survey to a working population in an attempt to clarify the relationships between self-reported nasal obstruction, observed apnea during sleep, and daytime sleepiness. A total of 7980 daytime workers were asked to complete questionnaires about nasal obstruction, apnea during sleep, and daytime sleepiness. Of the 7702 responses, the data from 4818 subjects were analyzed. Nasal obstruction and observed apnea were graded into 3 categories. Daytime sleepiness was assessed by the Epworth Sleepiness Scale. Subjects with chronic nasal obstruction had 5.22 and 2.17 times higher odds for having habitual observed apnea and excessive daytime sleepiness (EDS), respectively, compared with those without nasal obstruction ( P < 0.001). After adjusting for 3 potential confounding factors (age, sex, and body mass index) and the presence of habitual observed apnea, odds ratios for having EDS decreased, but still remained significant. Nasal obstruction is likely to cause daytime sleepiness, at least in part, by causing sleep-disordered breathing including apnea during sleep.