Teens become more sedentary as they age — and the more sedentary they are, the more likely they are to develop depressive symptoms — according to a study in the Lancet Psychiatry.
Roughly 2,500 young people wore accelerometers to measure their activity levels up to three times — at ages 12, 14, and 16. At age 18, they were assessed for depressive symptoms.
Sedentary behaviour increased and light activity (e.g., slow walking) decreased throughout adolescence. Each additional hour of sedentary behaviour per day at age 12, 16, or 18 was associated with significantly higher depression scores at age 18. Conversely, each additional 60 minutes of light activity at each time point was associated with significantly lower depression scores later.
The researchers write, "The displacement of sedentary behaviour with light activity in young people warrants more direct and specific consideration in physical activity guidelines and public health interventions aimed at reducing the prevalence of depression."