Nocturne is a Mac utility designed for users who require a less-troubling light from their display while working at night. The program lives on your Menu Bar from where you can access its Preferences panel and immediately change the way it operates on your Mac computer.
macOS provides you with a default solution for changing the color scheme of your display to make it easier for you to work at night time. However, the number of settings is quite limited as you can only schedule light changes and adjust the intensity of the display's light.
For this reason, programs like Nocturne were created: to provide you with additional light settings for your display. For example, the utility enables you to choose the preferred color to replace the white areas from your screen.
Furthermore, the tool also offers you options to hide desktop icons, disable window shadows, invert hue, etc.
The only thing I'd add would be the ability to define a global hotkey for immediately enabling Nocturne's light-changing feature. It isn't a big deal, it's just something I'd like to see in Nocturne.
In conclusion, you should definitely try Nocturne if you're looking for an easy and efficient way of changing the appearance of your display when you work late at night.