This sounds like your monitor is set too bright. (Or less likely, not bright enough.)
If you set your monitor to the same brightness that paper or a non-backlit screen would have in your room, then your vision doesn't have to adjust to the different brightness levels.
Same for TV. Don't watch TV in a dark room!
When I had a modest home theater with a projection TV (the old bulky kind, not a separate projector and screen), one of the best things I did was to light the white wall behind it with a soft neutral gray light.
The technique at the time was to use a small fluorescent desk lamp on a small table behind the TV, with the fluorescent tube wrapped in a specific color of lighting "gel" to make it a neutral gray. The lamp was aimed up at the wall behind the TV. This made everything much easier on the eyes.
If you set your monitor to the same brightness that paper or a non-backlit screen would have in your room, then your vision doesn't have to adjust to the different brightness levels.
Same for TV. Don't watch TV in a dark room!
When I had a modest home theater with a projection TV (the old bulky kind, not a separate projector and screen), one of the best things I did was to light the white wall behind it with a soft neutral gray light.
The technique at the time was to use a small fluorescent desk lamp on a small table behind the TV, with the fluorescent tube wrapped in a specific color of lighting "gel" to make it a neutral gray. The lamp was aimed up at the wall behind the TV. This made everything much easier on the eyes.