Donovan LM, et al. - Experts aspired to explore whether smoking-related risk for cardiovascular disease (CVD) rises with greater sleep-disordered breathing (SDB) severity (defined by clinical cutoffs of the apnea-hypopnea index). Polysomnography and smoking history were obtained without baseline CVD in 3,852 men and women in the Sleep Heart Health Study. In the adjusted proportional hazards model, they identified a significant three-way interaction between sex, current smoking and moderate to severe SDB. Among people with moderate to severe SDB, the risk of CVD associated with smoking in women is significantly higher.