The doctor told me that as long as it is 10,000 lux it is fine. For the best benefit after several long term studies were done, to use it in the morning for 20-30 minutes 18-20 inches away from you out in front of you but out to the side, never look directly at them; increases risks of cataracts. Any more than that showed no benefit. So I have it by me in the morning when I have breakfast or as I'm getting ready in the bathroom.

There is a light that I added to my routine as well, not 10,000 lux but less than that, that is on alarm that starts to come on gradually in the morning to wake me up. I have really benefited with this. As it is so dark in the a.m. and can't function without sun. It has helped as well with my depression and getting my day started; otherwise I am a slug this time of year.