It's a common misconception that you have to paint your walls white or a light color to reflect more sunlight and brighten a dark room. That'll work to an extent, but according to Sherwin-Williams, if you don't have a lot of light to begin with, there isn't much to reflect anyway.
So! You might consider going with a brighter, more pigmented color to help illuminate a room. One that can really enhance a dim space is gold, specifically a "clean" gold — the cleaner the color, the less black it contains, which keeps things light and bright. (Sherwin-Williams recommends Jonquil.)