A diagram illustrating how the Valkee is supposed to treat SAD
Many readers in the Northern Hemisphere are likely already starting to experience seasonal affective disorder, appropriately enough known as SAD. For those people fortunate enough not to be familiar with it, SAD is a mood disorder that is brought on by the shorter day-length experienced in winter – less sunlight results in gloomier people. One of the most common treatments involves regular exposure to bright artificial lights, that appear to psychologically serve the same purpose as sunlight. Now, one might assume that such light therapy would require that people see the light. According to the Finnish designers of the Valkee device, however, light also does the trick if you shine it up your ears.