Twilight aims to make your phone screen less damaging to your sleep cycle, operating on the idea that blue-shifted light screws up your circadian rhythms. There's some evidence behind this, but you could only put it to the test on your phone. Now you can take advantage of the sleep-friendly screen Twilight filters on your watch and TV as well.
When Twilight is activated, it adds a red filter to your display that should reduce the signals that tell your brain it's daytime. The new Android Wear version is tied to your phone. So, when the phone shifts into night mode with the red filter, your watch will as well. The Wear client also has a button that can disable Twilight on both devices.
The Android TV version of Twilight is not connected to your other devices, but it does have various scheduling controls to automatically activate a red filter at the necessary time. There are also settings for the color temperature, intensity, and more in the Android TV-style UI. The screen on your watch probably isn't getting enough use to affect your sleep, but the TV screen might.