Exercise has been show to lift the moods of people with depression, and a Swedish researcher said that it is because the activity stimulates the production of new brain cells.

Astrin Bjornebekk said that both antidepressants and exercise cause the new formations in areas of the brain responsible for memory and learning.

She said that exercise could therefore be an effective form of treatment for depression, especially when used along with medications.

The experiments that led to Bjornebekk's conclusions were performed on rats. Sometimes, results seen in animals do not translate directly to people.