Twitter Night Mode is here to help you scroll through tweets in the dark without hurting your eyes.
To activate Night Mode, just swipe from the left to bring out the navigation menu and tap on the “Night Mode” switch.
This move is meant to reduce the strain on your eyes, especially when there’s little to no surrounding light at night.
— Twitter (@Twitter) July 26, 2016
The new feature is not available on iOS for now, but it should be just a matter of time before that gets rolled out. Have fun!