If you spend long hours in front of a screen — especially after sunset — you've probably felt it: tired eyes, a slight headache, trouble winding down at the end of the day. Blue light from monitors is a real irritant, and the built-in Night Light in Windows, while decent, is pretty limited. LightBulb does the same thing, but better — fully automatic, highly customizable, and completely free.
🔆 What is LightBulb?
LightBulb is a free, open-source Windows application that adjusts your monitor's color temperature and gamma throughout the day. The idea is simple: during daylight hours, your screen stays at its normal cool, crisp color. As evening approaches, the app gradually shifts the display toward warmer tones — less blue light, more amber. By the time you're working late at night, it's significantly easier on your eyes.
It's been around for several years, has over 2,700 stars on GitHub, and is actively maintained by developer Tyrrrz. The codebase is written in C# and uses Avalonia for the UI — which means it looks clean and modern, unlike some older open-source tools that feel stuck in 2009.
✨ Features
🆕 What's New in Version 2.7
Version 2.7 was released in March 2026 and includes a solid batch of bug fixes and quality-of-life improvements. Here are the highlights:
📝 v2.7 Changelog Highlights
✔ Fixed UWP apps (like Microsoft Store apps) not showing up in the application whitelist
✔ Fixed "Pause when fullscreen" incorrectly triggering on taskbar thumbnail previews
✔ Fixed the task switcher (Alt+Tab) wrongly triggering fullscreen mode on Windows 11 25H2
✔ Fixed a crash (NullReferenceException) when detecting fullscreen or whitelisted apps
✔ Fixed dwm.exe CPU usage spike when monitors are turned off
✔ UI unloads when minimized to tray — less passive RAM and CPU consumption
✔ Added localization: English, Ukrainian, German, French, Spanish
✔ New LIGHTBULB_SETTINGS_PATH environment variable for portable/custom setups
✔ Proper app disposal on exit — cleaner shutdown behavior
⬇️ How to Install LightBulb
There are a few ways to get it. The simplest is the direct download from GitHub:
⬇️ Download LightBulb from GitHub
Grab the LightBulb.Setup.exe file (installs normally) or the LightBulb.zip if you prefer a portable version — just unzip and run. No .NET installation required since version 2.5; everything is bundled in.
If you use a package manager, you can also install it via command line:
winget install Tyrrrz.LightBulb
# Scoop
scoop install extras/lightbulb
# Chocolatey
choco install lightbulb
Note that package manager versions are community-maintained and might lag slightly behind the official release.
⚙️ How to Use It
Once installed, LightBulb starts automatically with Windows and sits in the system tray. First time you open it, you'll see a dashboard with a 24-hour cycle graph showing how your screen temperature changes through the day.
The main settings you'll want to configure:
Location: You can type in your city or coordinates. This is used to calculate sunrise/sunset automatically. If you'd rather not share location, just set manual times instead.
Day/Night temperature: Measured in Kelvin (K). The default daytime is around 6500K (standard white), and nighttime around 3900K (warm amber). You can push it warmer if you want — some people go as low as 2700K for late-night sessions. Experiment with what feels right.
Application whitelist: Go to Settings → Application Whitelist and add any apps that need accurate color — Photoshop, Lightroom, video editors, etc. LightBulb will automatically pause whenever those apps are in focus.
Hotkeys: You can assign a keyboard shortcut to toggle the app, increase/decrease temperature, or quickly disable it for 15 minutes (added in v2.6.1). Useful for quick adjustments without opening the full UI.
🔄 LightBulb vs Windows Night Light
Windows has a built-in Night Light feature in Display Settings, and it's fine for basic use. But LightBulb gives you a lot more control. Here's how they compare in practice:
Windows Night Light only lets you pick a fixed warm level on a slider, with no way to fine-tune in Kelvin. LightBulb lets you set exact temperature values for day and night independently. Night Light transitions happen on a fixed schedule; LightBulb calculates actual sunrise/sunset for your location. There's no whitelist feature in Night Light — it applies universally. And Night Light doesn't expose any hotkeys or command-line options.
If you're doing serious work on color accuracy or just want something more configurable, LightBulb is the better option.
💡 My Experience
I've been using LightBulb for a while now, and it's one of those tools that quietly earns its keep. I barely notice it's running — which is exactly the point. The transition from cool to warm happens so gradually that my eyes adjust without any awareness of the shift. I keep my nighttime temperature around 3500K, which takes a bit of the harshness off the screen without making everything look like I'm viewing it through an orange filter.
The v2.7 fullscreen fixes are genuinely useful. Previous versions would sometimes pause incorrectly when hovering over taskbar thumbnails — that's now gone. I also appreciate that the UI unloads from memory when minimized to tray. On a machine with a lot going on, that kind of restraint from a background app matters.
The only thing I'd say is that first-time setup might confuse users who aren't sure what Kelvin means. But once you've dialed in your day and night values, you never have to think about it again.
❓ Frequently Asked Questions
