Has anyone used a bright light therapy regime for treating depression or bipolar disorder?

My mom just bought me a Day-Light brand light. If you haven’t seen one its about the size of a small flatscreen t.v. The directions say recommended usage is 20–30 minutes a day. Over usage may cause irritability, excessive energy, or difficulty falling asleep at bedtime. Im curious if anyone out there has used this or a similar device. How did it affect you? Here is is a link to it. http://www.day-lights.com/