It might protect against cancer, as it did in mice. Researchers at The Ohio State University Comprehensive Cancer Center put mice in two different environments. One group were housed in standard laboratory cages, and the other group was placed into more crowded housing with 18 to 20 mice instead of the usual five per cage. The crowded cages also contained running wheels, tunnels, toys, mazes and nesting materials. When the mice were injected with cancer cells, the ones in the standard cages developed tumors within 15 days, but animals in the more exciting surroundings were much slower to develop tumors and those that did grow were 43 percent smaller than the ones seen in the mice in the uncrowded cages. The investigators also found that the animals in the stimulating environments had higher levels of stress hormones and stronger immune systems. Most notable, however, was a drop of almost 90 percent in the hormone leptin (produced in fat) in the stressed mice. In humans, high leptin levels are associated with an increased risk of certain types of cancer. The findings suggest that rather than avoiding stress we should be living "more socially and physically challenging lives," said lead researcher Matthew During.
Stress reduction techniques are still useful; just don't forget to be social.