Shameless plug: If someone is interested in using a program that has X as the only runtime dependency, you could checkout [0]. It is less a works-out-of-the-box solution, than a set of two tools you can integrate into your setup to shift screen color to your liking. It was inspired by [1].

[0]: https://github.com/graupe/brownout [1]: https://news.ycombinator.com/item?id=10575921