Browsing by Subject "päihteidenkäyttö"

Objectives: This master´s thesis examined the association between chronotype and substance use in “SleepHelsinki!” study, a population-based cohort of adolescent. Chronotype refers to a person’s partly biological tendency to a certain circadian rhythm, and the extremes are often called “early larks” or “night owls”. Based on earlier studies, the first research hypothesis was that later chronotype is associated with higher substance use. The second hypothesis was that social jetlag mediates the association between chronotype and substance use. Third hypothesis was that the association between chronotype and substance use is moderated by sex. Methods: All Finnish-speaking adolescents who lived in Helsinki and were born year 1999 or 2000 (N=7539) were invited to the study. The participation percent to an e-questionnaire was 18% and sample size was 1367 individuals, of whom 67% were girls. The indicator of chronotype was midpoint of sleep on free days. Social jetlag was measured as the difference between the midpoints of sleep on free days and days with obligations. Substance use was measured with AUDIT-C score and with the status of daily smoking and if the adolescent had tried recreational drugs. First hypothesis was analyzed with regression analyses, the second with mediation analysis and the third with moderation analysis. Results: Later chronotype was related to more substance use (p<0.001 for all measured substance use factors). This association was stronger in girls than in boys (p=0.033). However, social jetlag did not mediate the connection between chronotype and substance use (p=0.962). Conclusions: Our study contributed to the understanding on the association between later chronotype and higher substance use. The coexistence of these factors is useful information in the treatment of youth with sleep problems or substance use problems. The role of social jetlag in adolescents has to be studied more since the results of this study are in conflict with earlier research on social jetlag.