SAD was first systematically reported and named in the early 1980s by Norman E. Rosenthal, M.D., and his associates at the National Institute of Mental Health (NIMH). Rosenthal was initially motivated by his desire to discover the cause of his own experience of depression during the dark days of the northern US winter. He theorized that the reduction in available natural light during winter was the cause. Rosenthal and his colleagues then documented the phenomenon of SAD in a placebo-controlled study utilizing light therapy.