METHODS: The National Health and Morbidity Survey (NHMS) 2017 (n = 8230) was used for analyses. It was a nationwide survey conducted in Malaysia. The dependent variables were measured by three risk behaviors (cigarette smoking, alcohol drinking and use of illicit drugs). Probit regressions were utilized to examine the effect of mental health on the probability of smoking, drinking and using illicit drugs. Demographic and lifestyle factors were used as the control variables. Truancy was identified as a mediating variable.

RESULTS: Anxiety, depression and suicidal ideation affected cigarette smoking, alcohol drinking and use of illicit drugs through mediation of truancy. After controlling for demographic and lifestyle factors, students with anxiety, depression and suicidal ideation were more likely to smoke, drink and use illicit drugs compared with their peers without any mental health disorders. Furthermore, the likelihood of consuming cigarettes, alcohol and illicit drugs was found to be higher among students who played truant than those who did not.

METHODS: Sleep disturbances were measured in a sample of 65 youth with DS aged 6-17 years using the Children's Sleep Habits Questionnaire (CSHQ) and actigraph watches assessing sleep efficiency, sleep duration and wake after sleep onset. Behavioural challenges were evaluated through externalising and internalising subscales of the Child Behavior Checklist (CBCL) and of the Scales of Independent Behavior, Revised (SIB-R).

RESULTS: The findings demonstrated that over a period of time, sleep problems are significantly associated with both externalising and internalising behaviours as measured by CSHQ and CBCL, even after accounting for the effects of IQ and SIB-R Broad Independence. No significant correlations were observed on a daily basis over seven consecutive days, as measured by actigraphy and both externalising and internalising indices of SIB-R.