For the love of Frick, if you compute in a dark/dim room please hook up a light to illuminate the wall behind your screen. It doesn't have to be the sun! Just a fraction of your screen's brightness, really.
If you want to be very fancy you can refer to it as "bias lighting" but that's going to bring up a lot of expensive specialty products and buzzwords and tech specs if you look it up. A $2 USB light from the dollar store can do just fine; Just look for anything that disperses/softens the light instead of shining a harsh beam.
The reason for this: Eye fatigue!
When you only have dark surroundings and a bright screen in front of you, your eyes have to do a lot of extra work adjusting all the time to such a harsh contrast. Adding even a dim light against the wall makes it easier on them, adding a step in the middle.
(Visual artists: You know how it's easier on your eyes to work for longer periods on a grey canvas instead of white? Similar concept!)
Before I go, one more tip!
The 20/20/20 trick is worth remembering to prevent and ease eye strain: Every 20 minutes, look at something 20 feet away for 20 seconds.
(That's about 6 meters for those of us who measure things in Normal, but "20/6/20 trick" really isn't all that catchy now, is it?)
