Winter depression or Seasonal Affective Disorder(SAD) is not all that well understood, but is believed to be linked to the lack of sunlight in the winter months. Winter depression involves suffering from feelings of gloom, anxiety and lethargy as the days get longer and nights get shorter. Other SAD symptoms include overeating, especially on high carbohydrate foods, and sleeping for longer than usual. Researchers have now found that light therapy helps in countering winter depression. The therapy, which involves exposure to bright light from a specially designed box, helped three out of four of those with SAD. The light has to be as intense as the light outdoors just after dawn or before sunlight. The exposure needed for a therapeutic effect varies from 15 minutes to two hours a day. SAD, whether mild or severe, has serious implications and needs medical help. Antidepressants, psychological therapy and relaxation could also benefit those suffering from SAD.