Independent and Joint Associations of Chronotype and Sleep Quality with Psychoactive Substance Use in Adolescents

Objective To examine the associations of chronotype and sleep quality with psychoactive substance use among adolescents attending schools with different schedules and patterns associated with chronotype–school schedule combinations. Methods A cross-sectional study was conducted in 1,311 adolescents aged 11–19 years from public and private schools. Chronotype was assessed using the Children's Morningness–Eveningness Questionnaire, sleep quality using the Pittsburgh Sleep Quality Index, and psychoactive substance use through structured questionnaires. Logistic regression models examined the independent and joint associations of chronotype and sleep quality with psychoactive substance use. Formal Chronotype × School Schedule interactions were also tested. Results Most adolescents reported insufficient sleep (65% slept <8 h/night) and regular or poor sleep quality (80%). Morning-shift students reported shorter sleep duration than evening-shift students. In separate adjusted models, evening chronotype and poor sleep quality were associated with higher odds of alcohol, tobacco, and cannabis use. In fully adjusted models, sleep quality remained the most consistent predictor across substance categories, whereas chronotype associations were substantially attenuated. Formal Chronotype × School Schedule interactions were not statistically significant for alcohol, tobacco, or cannabis use. However, analyses using a combined chronotype–school schedule variable identified significant differences in alcohol, tobacco, and cannabis use patterns across chronotype–school schedule groups. Conclusions Sleep quality showed the most consistent associations with psychoactive substance use across multiple substance categories. Although the school schedule did not significantly modify chronotype-related associations, chronotype–school schedule combinations were associated with distinct substance-use patterns. These findings highlight sleep health as a potential target for adolescent substance-use prevention.