LightBulb is a free utility tool that was created by indie dev Alexey Golub for PC. This open-source software can be used to dynamically adjust gamma levels being displayed by monitors. It does so based on the time of day as it transitions from morning to afternoon, and night.
LightBulb utilizes a similar concept to F.lux or CareUEyes in that it attempts to reduce eye strain by changing the color temperature of computer monitors from the cool blueish shade to a warmer and more relaxing orange color. It's easy to set up and boasts a simple and intuitive user interface.