NightOwl is a super simple Mac app that’s designed to give you more control over Dark Mode for macOS Mojave. It adds a Dark Mode toggle to the menu bar so you can turn Dark Mode on and off without needing to open up System Preferences. You can also set Dark Mode to a timer or have it come on when the sun sets using NightOwl.
Link: Author
Download: NightOwl 0.2.9
Old Version:
NightOwl 0.2.7