A large Norwegian study found that students who exercised infrequently were more likely to develop clinically defined depression, anxiety, or another common mental disorder over the following year. How often they exercised appeared to matter more consistently than how hard or how long they worked out.

The findings were published in the open-access journal PLOS One by Michael Grasdalsmoen of Western Norway University of Applied Sciences and his colleagues.

Why Student Mental Health Matters
Depression and anxiety are leading causes of disability among young adults worldwide. The transition into higher education can bring academic pressure, financial concerns, disrupted routines, and separation from familiar support systems, making this period an important window for prevention.

Exercise has long been associated with better mental health, but much of the earlier evidence has relied on snapshots taken at a single point in time. Fewer studies have followed students prospectively and then used a standardized diagnostic assessment to identify mental disorders.

To examine how different exercise habits might shape later risk, the researchers tracked 10,460 full-time students in Norway between the ages of 18 and 35.

Frequency May Matter Most
At the beginning of the study, participants reported how frequently they exercised, how demanding the activity was, how long their sessions lasted, and their total weekly exercise time. One year later, they completed a self-administered diagnostic instrument that assessed common mental disorders.

Students with lower overall activity levels were more likely to meet clinical criteria for anxiety or depression at follow-up. Of the different measures examined, exercise frequency produced the most consistent association with mental health.

The patterns were not identical for everyone. Among women, lower exercise intensity predicted anxiety and depression, while among men, shorter weekly exercise duration emerged as a stronger risk factor...