The blue light that is emitted by computer screens makes it hard to keep our melatonin levels high at night. f.lux is designed to help with this by automating screen brightness as the sun goes up and down. It is free for Windows and can be downloaded here.
In Settings you can choose a brightness for the day and the night, and enter your latitude. In Edmonton, this is 53.5472° N, 113.5006° W. You can find this by googling the latitude of your nearest large town or city.
f.lux features an override button, if you are working on something that is colour sensitive.
While it’s not difficult to change screen brightness, f-lux means you never have to think about it again. (http://f-lux.en.softonic.com/)