The association between sleep disturbance and second-hand smoke exposure: a large-scale, nationwide, cross-sectional study of adolescents in Japan

Objective: This study investigated the association between secondhand-smoke (SHS) exposure and sleep disturbance symptoms. Methods: This study was a cross-sectional survey of junior and senior high school students throughout Japan. A total of 85,931 adolescents responded, and 84,988 questionnaires were included in the analysis. Results: Adolescents who had never smoked accounted for 88.0% of respondents; among that group 39.1% reported having been exposed to SHS over the previous week. The results of multiple logistic regression analyses indicated that the adjusted odds ratios for insomnia symptoms such as difficulty initiating sleep (DIS), difficulty maintaining sleep (DMS) and early morning awakening (EMA), as well as sleep disturbance symptoms such as subjectively insufficient sleep and short sleep duration (<6 h), tended to be higher both among never-smoking adolescents with SHS exposure and among smoking adolescents, as compared with never-smoking adolescents without SHS exposure. When adolescents with one or more of DIS, DMS, and EMA were defined as having insomnia, the adjusted odds ratio for insomnia was highest for adolescents who smoked, followed in descending order by those exposed to SHS both inside and outside the home, those exposed to SHS only inside the home, those exposed to SHS only outside the home, and never-smoking adolescents without SHS exposure (p < 0.001). Conclusions: The present study has revealed that SHS exposure is associated with sleep disturbance. Thus, in addition to smoking cessation programs, it is also necessary to endorse measures to protect adolescents from SHS exposure in order to promote good sleep in this population.