Google isn't going to sit on the sidelines while Apple and Microsoft bring night modes to their platforms. Users have discovered that Canary builds of Chrome OS now include an experimental night mode (Night Light, to be exact). Flick it on and it'll give the screen a yellowish tint that cuts down on blue light and, theoretically, helps you sleep. At the least, it should be easier on your eyes during those late-night Chromebook sessions.
As with any Canary build, though, you'll have to put up with a lot to get this feature early. Aside from going through the process of switching to the Canary update track (we hope you're comfortable with command lines), you'll have to run a decidedly buggy operating system. Be ready for crashes and other hiccups. If you can't bear without a little web surfing before bed, though, it might be worth the sacrifice until night mode reaches stable Chrome OS versions.