If you are on mac, you should check 'f.lux'. It will adjust the colors of the screen automatically to minify the effects of blue light.
Redshift seems to be the top choice for Linux users though, because f.lux lacks some basic features (like being able to turn it on during daylight hours). The trade-off is that f.lux is easier to install and has a smaller footprint.
Also worth noting is that Redshift is FOSS, and f.lux is not (though there are forks on githib, so I must be missing something).