[Update: Noooope] The highly-requested dark mode will be available in an upcoming Android release
(Android Police)

Update 1: 2018/02/23 4:34pm PST Google has walked back the system-wide dark mode promise once again, blaming a miscommunication with the team that handles AOSP issues. The dark mode isn`t coming just yet, but rather If there`s one feature that people have consistently been clamoring for from Android, it`s dark mode. As it turns out, people don`t always like staring at masses of bright white, especially when they`re in dark environments. Read More[Update: Noooope] The highly-requested dark mode will be available in an upcoming Android release was written by the awesome team at Android Police.