Let the sunshine! Let the sunshine in! Why? Because according to the American Journal of Epidemiology, exposure to sunlight may reduce the risk of breast cancer.

The study says because the "body manufactures the active form of Vitamin D" that could help reduce risk of breast cancer. 1,788 women with cancer and 2,129 without participated in the study. The test measured the women's skin pigmentation on their foreheads and the upper inner arm as a measure of sun exposure.

"We believe that sunlight helps reduce women's risk of breast cancer because the body manufactures the active form of vitamin D from exposure to sunlight," lead author Dr. Esther M. John, from the Northern California Cancer Center in Fremont, said in a statement.

"It is possible that these effects were observed only among light-skinned women because sun exposure produces less vitamin D among women with naturally darker pigmentation."

The study is not the first to link sun exposure with a reduced risk of breast cancer, but the way that sun exposure was measured was new, according to John.

High levels of sun exposure were associated with a 47-percent reduced risk of advanced breast cancer in light-skinned women, the results show. Mutations of the vitamin D receptor gene did not affect the association.

However, this association was not seen in women with medium or dark skin and was only apparent for advanced disease, not localized breast cancer.

The results could have important public health implications, but they will require confirmation in other studies, the authors conclude.