I have one of these on my desk, right next to the monitor. Working in front of it for 30-60 minutes a day really helps. Live at 60.5 degrees north. Also take vitamin suppliments and exercise more in winter; it's hard to tell what causes the improvement. With a lamp like this, you don't have to do anything outside of your routine to get more light. You can keep it 20 centimeters (~1 foot) from your eyes, so reduced irradiance due to distance (as this article points out) is not a problem.
http://www.usa.philips.com/c-p/HF3318_60/energylight