To Improve your Mood, Play in the Dirt

“When I go into the garden with a spade and dig a bed I feel such an exhilaration and health that I discover that I have been defrauding myself all this time in letting others do for me what I should have done with my own hands.” ~ Ralph Waldo Emerson (1803-1882)

“In forty years of medical practice, I have found only two types of non-pharmaceutical ‘therapy’ to be vitally important for patients with chronic neurological diseases: music and gardens.” ~ Oliver Sacks, MD (1933-2015)

At San Francisco General Hospital, where I used to work, there is a place called The Comfort Garden. It was created in 1990 as a memorial for staff who had died, mostly of AIDS. It is an oasis for patients, families, staff members, and visitors; a place to rest, to recollect, to reflect. Gardens lend themselves to such moments.

When I needed a short break from my work with trauma patients—people with gun shot wounds, stab wounds, fracture, burns, and crush injuries—I went to the garden. Something was always in bloom, even in winter. Sitting on a garden bench, hyper-focused on the mass of flora before me, green became more than just green; it was celadon, jade, forest, chartreuse, and olive. Yellows were lemon, ocher, amber, citrine, and egg yolk. Purples were aubergine, indigo, violet, and lavender. Ten minutes of garden time was all it took to refresh me.

The Comfort Garden at SFGH inspired me to create my own comfort garden at home. It became my refuge, my palette, my own nature preserve— a spongy organic cushion that helped to absorb the day’s trauma. Digging in the dirt after work and on weekends always made me feel better and sometimes, even exhilarated.

Recently, I was thrilled to find out that the elevated mood I experience while gardening may in part be due to my inhaling a microbe commonly found in the dirt called Mycobacterium vaccae, a cousin of the bacterium that causes tuberculosis. 

In a 2011 article in Horticulture entitled, Dirt Can Make You Happy, author Naomi Sachs writes about an English oncologist, Mary O’Brien, who noticed clinical improvement in her lung cancer patients after she inoculated them with a serum containing M. vaccae. Building on this discovery, Dr. Chris Lowry, an associate professor in the Department of Integrative Physiology at Colorado University in Boulder, injected Mycobacterium vaccae into mice. The resulting immune response caused the brain to produce serotonin, a neurotransmitter involved in mood regulation and decreased stress response. Currently, Dr. Lowry is conducting clinical trials to test the use of M. vaccae in the treatment of PTSD in military vets. Maybe it’s no coincidence that many Veteran Administration Hospitals provide horticulture therapy programs for vets. 

With rain in the near future, fall is the perfect time to plant bulbs, shrubs, and trees. While you are digging in the dirt, remember to inhale—deeply—and enjoy the mood-enhancing effects of M. vaccae.