Substance use and stress trajectories impact sleep trends in Swedish adolescents – the STARS cohort

Background

Adolescence is a critical period when adverse mental health, substance use and sleep problems often first emerge, and sleep patterns change. Despite sleep’s central role in overall health, longitudinal associations between stress, substance use, and adolescent sleep are largely understudied. Thus, this study aimed to explore how lifestyle factors and their trajectories affect sleep outcomes over time in adolescents aged 13 to 18 years.

Methods

We used data from 3 timepoints (ages 13, 15 and 18) from the longitudinal STARS (Study of Adolescence, Resilience and Stress) cohort (n = 2223, 55.5% female). We assessed trends in substance use, stress and sleep using latent growth models and logistic mixed models. Substance use included smoking, snus use, and consumption of high- and low alcoholic drinks. Sleep outcomes included sleep duration, social jetlag (SJL, difference in sleep midpoint between schooldays and non-schooldays), insufficient sleep and sleep onset difficulties (SOD). We analysed cross-process associations of stress and substance use with sleep using parallel process latent growth curve models.

Results

Across adolescence, sleep problems increased, as evidenced by declining sleep duration (8.6h at age 13 to 7.6h at age 18) and growing prevalence of insufficient sleep (14.3% to 52.0%) and SOD (19.4% to 25.4%). At baseline, all substance use measures were cross-sectionally associated with adverse sleep outcomes. Longitudinally, increasing substance use was predominantly associated with shorter sleep duration, greater SJL and a higher likelihood of insufficient sleep, with weaker associations for SOD. Higher stress was associated with unfavourable sleep outcomes at baseline and increased stress over time was associated with adverse changes in sleep duration, insufficient sleep and SOD.

Conclusions

Our findings highlight the importance of interventions and policies targeting substance use reduction and stress management to improve sleep health.

Key messages

• Sleep outcomes worsen from age 13–18 with shorter duration and more insufficient sleep and sleep onset difficulties. Rising substance use and stress are key drivers of poorer sleep over time.

• Increasing stress and substance use predict shorter sleep, more social jetlag, increasing insufficient sleep and insomnia, highlighting prevention targets to improve adolescent sleep health.