LightBulb is a f.lux-like application which smoothly adjusts screen gamma to make colours seem warmer at night, reducing eye strain and making your PC more comfortable to use.

Install the program and it goes to work automatically, detecting your location, figuring out the sunrise and sunset time and updating your display colour temperature to match.

LightBulb does its best to ensure these new settings stick, refreshing them every five seconds to prevent other apps making changes.

This worked well for us, but if you have any issues or just want to find out more, LightBulb’s settings dialog can probably help. Right-click its system tray icon and select “Configure” to check them out.

A handy “Preview 24-hour cycle” option quickly shows how your display colour temperature will change throughout the day. If that’s too much, or too little, use the sliders to adjust the daytime and night time colour temperatures and hit Preview to see the change.

Smoothly adjust the a monitor’s colour temperature to suit the time of day

Disabling “Gamma Polling” stops LightBulb’s constant refreshing of your gamma settings, enabling other apps to take control.

There’s also an option to disable the effect when you’re working on a full-screen application, convenient when you’re running graphics or design applications and need an accurate, consistent view of colours.

If this still isn’t enough, you’re able to disable the program on demand. Alternatively, just close the program at any time and your display will instantly return to normal.

One issue we noticed is that LightBulb seems to detect location via your external IP address, which could be a problem if you’re using a VPN when it launches. We didn’t see any way to bypass this or choose the location manually, either.

Still, otherwise LightBulb works as advertised, has some useful configuration options, and is being so actively developed that new features are arriving every few days. Check it out.

LightBulb is an open-source application for Windows 7 and later.