Chronic nasal congestion at night is a risk factor for snoring in a population-based cohort study

Background: Nasal congestion at night is thought to have a role in snoring and sleep apnea, but this hypothesis has not previously been tested in a po pulation-based study. Methods: Baseline and 5-year follow-up data on self-reported nocturnal nasa l congestion and snoring frequency were collected from a population-based s ample of 4916 men and women (age range, 30-60 years at baseline) enrolled i n the ongoing Wisconsin Sleep Cohort Study. In-laboratory polysomnography w as performed on a subset (n = 1032) of the study population to determine th e frequency of apnea and hypopnea episodes during sleep, Logistic regressio n was used to estimate odds ratios for snoring with chronic nasal congestio n at night. Results: Nocturnal nasal congestion frequency was independently associated with snoring frequency in cross-sectional analyses. The odds ratios (adjust ed for sex, age, body habitus, and smoking) for habitual snoring with sever e (always or almost always) nasal congestion vs none was 3.0 (95% confidenc e interval, 2.2-4.0). This association was not explained by habitual snorer s with frank sleep apnea (ie, greater than or equal to5 apnea and hypopnea episodes per hour of sleep). Prospective analyses showed that persons with chronic severe nasal congestion had a high risk of habitual snoring accordi ng to the data from the 5-year follow-up survey: the odds ratio for habitua l snoring and reporting congestion always or almost always at both baseline and follow-up was 4.9 (95% confidence interval, 2.8-8.8). Conclusions: Nocturnal nasal congestion is a strong independent risk factor for habitual snoring, including snoring without frank sleep apnea. Interve ntion studies are needed to determine if snoring can be reduced with treatm ent of nasal congestion.