Associations of unhappiness with sociodemographic factors and unhealthy behaviours in Chinese adolescents.

Background: Evidence on the effects of lack of physical exercise, alcohol drinking and smoking on happiness is limited and inconsistent. We examined the associations of unhappiness with sociodemographic factors and these unhealthy behaviours in Chinese adolescents. In a school-based survey in 2012-13 in Hong Kong, 45 857 secondary school students (mean age 14.8 years, 54.0% boys) reported their happiness level (not happy at all/not very happy/happy/very happy), frequency of physical exercise, alcohol drinking status, smoking status and sociodemographic factors. A main and a sensitivity analysis examined the associations of unhappiness with the study factors, treating unhappiness as a binary (combining 'not happy at all' and 'not very happy') and a four-level ordered variable, respectively. The main and the sensitivity analysis both showed that unhappiness was associated with older age, very poor families, non-intact families, more co-residing smokers, lack of physical exercise and alcohol drinking; current smokers were unhappier than never and ex-smokers; unhappiness also increased significantly with the number of unhealthy behaviours ( P for trend < 0.001). In Chinese adolescents, unhappiness levels were higher in those who had a very poor family, a non-intact family and more co-residing smokers, and in those who were physically inactive, drank alcohol and smoked.