On average, when looking at the change between year 7 and 10, every one-hour increase in sleep per night was linked to a 9% reduction in psychological distress.
Each added day of 60 minutes of moderate-to-vigorous physical activity per week was linked to a 3% reduction in psychological distress. Each added daily serve of fruit or vegetables was linked to 4% lower psychological distress.
By contrast, each added hour of screen time was linked to a 2% increase in psychological distress, as was each unit increase in junk food or sugary drinks.
Because drinking alcohol and smoking are less common in early adolescence, we only looked at whether they had or hadn’t drank alcohol or smoked in the past six months. We saw that switching from not drinking in year 7 to drinking in year 10 was associated with a 17% increase in psychological distress. Switching from not smoking to smoking was linked to a 36% increase in psychological distress.
It’s important to note our study can’t definitively say lifestyle behaviour change caused the change in distress. The study also can’t account for changes in a student’s circumstances such as in their home life or relationships. With the baseline survey done in 2019 and the year 10 survey done in 2022, there was also the potential impact of COVID.
But our longitudinal design (tracking the same subjects over an extended period) and the way we structured the analysis does help illustrate the relationship over time.
Our study didn’t measure vaping, but evidence shows that, like smoking, it has clear links with adolescent mental health.