As the months grow colder and darker, many people find themselves somewhat sadder and even depressed.
Bright light is sometimes used to help treat the symptoms of seasonal affective disorder, or SAD. Researchers are now testing light therapy to see if it also can help treat depression that's part of bipolar disorder.
It's unclear how lack of light might cause the winter blues, although some suggest that the dark days affect the production of serotonin in the skin.
The idea with light therapy for depression is to replace the sunshine lost with a daily dose of bright white artificial light. (Antidepressants, psychotherapy and Vitamin D help, too, according to the National Institute of Mental Health.) The light box is actually more like a screen, the size of your average desktop computer. Some people call it a "happy box."