Seconding f.lux. (I don’t use dark themes[1] per se, but I do sometimes use f.lux’s “Darkroom Mode” feature, which has a similar effect.)
The brightness question is impossible to give a canonical answer to, because how bright your monitor should be depends on ambient illumination. It should be bright enough to see, but not so bright that it hurts your eyes. What that means in practice depends on where you are and what light is shining where, etc.
[1] Anyone who likes dark themes and uses GreaterWrong: check out both the Dark theme (theme selector button ‘B’) and, also, the theme tweaker’s “Invert colors” setting!
Seconding f.lux. (I don’t use dark themes[1] per se, but I do sometimes use f.lux’s “Darkroom Mode” feature, which has a similar effect.)
The brightness question is impossible to give a canonical answer to, because how bright your monitor should be depends on ambient illumination. It should be bright enough to see, but not so bright that it hurts your eyes. What that means in practice depends on where you are and what light is shining where, etc.
[1] Anyone who likes dark themes and uses GreaterWrong: check out both the Dark theme (theme selector button ‘B’) and, also, the theme tweaker’s “Invert colors” setting!