Basically, if you are using it late at night you are getting light therapy at the wrong time though.
I'm currently doing an experiment where I turn off the computer at 11pm to see if it makes it easier to fall asleep earlier. This is harder to stick to than it sounds at first glance though.
There is a good evidence for it: http://en.wikipedia.org/wiki/Light_therapy
Basically, if you are using it late at night you are getting light therapy at the wrong time though.
I'm currently doing an experiment where I turn off the computer at 11pm to see if it makes it easier to fall asleep earlier. This is harder to stick to than it sounds at first glance though.