i have sensory processing problems due to asd so i have this shit fairly well covered.
f.lux is a desktop application that cuts out the blue light on your screen - its really good, basically makes your screen fairly orange, and you get used to it fast. turn it off when youre doing colour though, dear lord.
also, make sure to keep your screen the same brightness as your surroundings - this might mean turning up your lights at night.
you can also get a lot of extensions to darken browsers and that, which are worth looking into.
worst comes to worst, though, wear sunglasses. ive done this, but again, do not wear them during the colour process.