Here is news from the BBC: getting dirty may make you happier.
Exposure to dirt may be a way to lift mood as well as boost the immune system, UK scientists say.
Lung cancer patients treated with "friendly" bacteria normally found in the soil have anecdotally reported improvements in their quality of life. Mice exposed to the same bacteria made more of the brain's "happy" chemical serotonin, the Bristol University authors told the journal Neuroscience. Common antidepressants work by boosting this brain chemical. A lack of serotonin is linked with depression in people. The scientists say more work is now needed to determine if the bacterium Mycobacterium vaccae has antidepressant properties through activation of serotonin neurons.
On the other hand, serotonin can decrease sexual activity and delayed ejaculation:
"The more you bathe people in serotonin, the less they need to be sexual," says Joseph Marzucco, MSPAC, a sex therapist practicing in Portland, Oregon. "(It) can just devastate sexual desire."