Some people were quite displeased by Google's move to a white system theme in Android 5.0 Lollipop. It can be quite retina-searing in a dark room, but the Android M preview offers a solution. In developer options is a menu that enables a new material dark system mode. Behold.

The theme option has settings for light (the default), dark, and automatic. If you turn on dark mode, all the settings screens will switch over to material dark. This doesn't affect apps or any other part of the device, as far as I can tell. I'm not sure what the automatic setting does, but I assume it'll somehow switch from light to dark at a predetermined time. At night, I suppose? There aren't any settings for it that I can see.

Keep in mind this is a developer preview. The dark mode might remain in the develop options for the final release, or it could be a regular setting. It may also be gone entirely for all we know. You can give it a shot if you've got a compatible device and want to download the preview.