Studies have shown time spent in nature does us all good. Specifically a recent study done with 1,200 people, published in the journal Environmental Health and Technology found that even just five minutes in a leafy park can significantly boost our mood. Well it might be because we inhaled some bacteria among the leaves and grass.

It’s called mycobacterium vaccae and research presented today at the 110th General Meeting of the American Society for Microbiology found that it might also increase an ability to learn.

Injecting this bacteria into mice has already been shown to increase serotonin levels and decrease anxiety. But the researchers wondered if it might have a subsequent effect on learning. They fed the bacteria to mice and then tested them in a maze.

And lo and behold these mice navigated the maze twice as fast as mice who received no bacteria.

But here’s a caveat: When they tested bacteria-fed mice three weeks after removing the single-cell organisms from their diet they found that these mice were still faster than the mice who never received the bacteria. The difference, however, was not significant. So the results are temporary.

Of course this is all in mice. Still, it might give a clue to why we get a boost in mood and clear thinking, when we just take a simple stroll through the woods.

—Christie Nicholson