The link between time spent sedentary and poor health is very well established. We should all strive to be more physically active, as this can cancel out some of the worst effects of prolonged sitting, such as heart disease, increased blood pressure, and weight gain.

It’s not just about your physical health. Sitting for hours and hours is also linked to symptoms of anxiety and depression. However, not all forms of sitting are equal in their mental health impact.

Researchers at the University of São Paulo, led by André Werneck, embarked on a new study aiming to untangle the biological factors linking sedentary behavior to depression. They explored inflammatory markers, blood sugar levels, and body measurements like waist circumference. These factors were previously linked to mental health conditions.

Analyzing over 4,000 participants from the 1958 National Child Development Study in the UK, the researchers found a pattern they didn’t expect: mentally-passive activities like watching TV were associated with a 43% higher risk of depression, unlike mentally-active behaviors like working at a desk or driving that weren’t associated with depression.

Concerning biological factors, the study points to obesity and inflammation, measured by waist circumference and C-reactive protein, as partial explanations for the risk of depression. Diet and exercise are key to mitigating these risks. However, blood sugar levels, as indicated by glycated hemoglobin, didn’t show a significant impact somewhat surprisingly.

Virtually all public health guidelines recommend that you spend a decent amount of time per week exercising to combat some of the negative physical and mental health effects of sedentarism. One 2023 study found that sedentary people who perform 30 to 40 minutes of daily moderate to vigorous intensity physical activity have the same risk of death as those with low amounts of sedentary time.

This new research, however, adds a new dimension to combat the ill effects of prolonged sitting. In addition to physical activity, perhaps guidelines could be revised to also advise against spending too much time in a mentally passive state. For instance, people may be well advised to take a break from TV to engage in more mentally stimulating activities such as solving puzzles.

“While physical activity guidelines recommend reducing and breaking up sedentary time, our findings suggest that recommendations specific to mental health could emphasize reducing mentally-passive sedentary time,” the authors wrote.

The findings were reported in the Journal of Affective Disorders.