I got myself a SAD light and I have been using it this morning. Wow. And this thing is only 4500 at 6 inches. I can hardly imagine what 10,000 would be like! I can position it almost exactly 2 feet from my eyes while I work at my computer. After about an hour and 20 minutes, my eyes are feeling a little fatigued. Gonna knock it off for now, maybe try it again for an hour this afternoon.