There is the result of what my searches:
Black text on white background: It's far better for reading. If you read books, you don't have to "rewire" your brain each time you switch.
BUT the major problem is the blue light coming out of the screen. It literally destroys your sleep cycle, since your inner clock is actually calibrated by your eyes, through blue light. Moreover, the skin actually reacts to blue light.
However, we still don't know what are the real effect of screens on eyes. There is literally, in my home country, an epidemic of myopia. The current scientific literature is actually saying that light coming out of screens actually encourage the formation of myopia. But who knows, what we will unveil in the future about the true nature of this.
To conclude: Blue light (and i'm pretty sur you can generalise at light from screens) is dangerous for yourself. But It's far better to read black text on white background. The solution is to use redshift, with overkilled configuration to make your monitor as orange as possible in the evening. And to use your computer far less. The other solution is to still use redshift, but with white text on black background. I personally read a lot, so I don't want to do the switch, but if you don't care, I would say that for your own health sake, try to emit as low light from your screen as possible. And so use black background with white text.