Why does this tune come to mind...
Always Look on the bright Side of Life ...
Mind that due to the smaller opening of the pupils when looking at lighter environment, light background helps focusing. Though depending on personal conditions either dark or light can be better.
Light of course does not mean using your screens as floodlight. And light only works well if the rest of your room is proper lit, and also correctly lit as to make sure there is no glare or reflection.
Mind that - for all that I know - reading a paper book should also be done in a well lit environment. Doing this in the semi dark - so I have been told countless times - does risk damage to ones eyesight. That said, A dark scheme can be used in a well lit environment. (I guess?).
Also mind, that probably lots depend on the quality of the monitor. And proper setup of it.
Any way - ask you doctor. And also ensure to pay attention to all other health issues related to screen work.
And no, "bugs are attracted to the light" is not an argument.
