['Alcohol consumption as well as overweight is known to aggravate the severity of sleep-disordered breathing (SDB), but little is known about alcohol consumption in truck drivers. The aim of this study was to examine the relationship between alcohol consumption and SDB among truck drivers.', 'We conducted a cross-sectional study of 1,465 men aged 20-69 years who were registered with the Japanese Trucking Association. The 3% oxygen desaturation index (3%ODI) was selected as an indicator of SDB, representing the number of desaturation events per hour of recording time in which blood oxygen fell by > or =3% based on overnight pulse-oximetry. Participants completed a self-administered questionnaire including alcohol consumption on the same night for SDB assessment.', 'The prevalence of 3%ODI > or =5, > or =10, and > or =15/h was 25.4%, 11.1%, and 6.6% respectively. The multivariable odds ratios (OR) of 3%ODI > or = 10/h were 1.5(0.9-2.5) for 0.5 to <1.0 g of alcohol intake/kg and 3.4(1.8-6.6) for > or =1.0 g of alcohol intake/kg compared with non-drinkers. Similar associations with alcohol consumption were observed for 3%ODI > or =5 and > or =15/h. The relation between alcohol consumption (> or =1.0 g of alcohol intake/kg) and 3%ODI > or = 10/h tended to be more evident among men with body mass index (BMI) <23.4 kg/m(2) than those with BMI >or = 23.4 kg/m(2) [11.4 (3.2-41) vs. 1.2 (0.6-2.7), p = 0.18 for interaction]. A similar trend was observed for 3%ODI > or= 5/h.'] Is alcohol consumption before sleep associated with severity of sleep-disordered breathing among professional Japanese truck drivers?