SunsetScreen Review (Windows)

SunsetScreen is software for blue light reduction.

Made by Daniel White in 2015 SunsetScreen is similar to f.lux, Redshift, Night Shift and to Iris blue light feature.

Something which makes SunsetScreen better than f.lux is the ability to set custom night duration by time rather than location and the ability to set day and night brightness aside from color temperature only.

All features and customization of SunsetScreen are free which is benefit over Iris. Iris is also free, but customizations are part of the Pro version.

The goal of this article is to show you how to download, install and use SunsetScreen, to explain what each button does and how to master this awesome program.


You can download SunsetScreen from the official website. Go to

And click the Download link. Note that SunsetScreen is available only for Windows

You can also download the portable version of SunsetScreen by clicking

Save the file somewhere on your PC. We are going to install SunsetScreen after a moment.

SunsetScreen requires .NET Framework 3.5 which you can download from here.

If for some reason the site is not available or the project is abbadoned in the future use this button to download the latest version of SunsetScreen.

[Download not found]

Or download the SunsetScreen portable version

[Download not found]


After you download SunsetScreen you will see the setup icon

Double click it or right click and choose Open

SunsetScreen installer requires Admin right. When the User Account Control windows pops up click Yes

The SunsetScreen installer will now open

In the center of the screen you will see infomation about the publisher and the official SunsetScreen website.

For any questions you can also e-mail Daniel White at SunsetScreen installer should also be digitally signed with Comodo SHA256 algorithm.

This signature ensures that the installer is safe and is not modified by hackers to make changes to your system.

Clicking About… button of the instasller will show you which software is used for the creation of the installer.

SunsetScreen installer is made by using the InstallMate software.

You can find more info about InstallMate from the official website

You can also cancel the installation at any time by clicking the Cancel button or the X button in the top left corner of the installer window.

You would be asked for confirmation

Clicking Yes will cancel the installation and you will get Installation cancelled window.

And clicking Finish will close this window. Instead of Yes we are going to click No instead to continue with the SunsetScreen installation.

From the installer windows click Next

You will see the SunsetScreen license agreement

Before clicking Next you should know that you can’t use SunsetScreen for commercial purposes. Of course you are not going to sell it, but you can’t use SunsetScreen at your workplace. You can only use it at home for personal use.

I guess this is the monetization model of SunsetScreen, but if you want to use SunsetScreen at work first write to Daniel White for permission.

Since f.lux is also not permitted at your workplace if you want blue light reduction software in your office you can try Iris or Iris mini. They both have free versions which can be used at commercial setting.

If you are going to use SunsetScreen at home for non-commercial purposes click Next

You will see the Installation options window

SunsetScreen requires 764KB of disk space and by default will install itself into

C:\Program Files (x86)\SunsetScreen

You can change this location by clicking the Browse… button

This will open a window which you can use to change the installation folder

SunsetScreen will also automatically create shortcuts. You can disable the shortcuts creation by unchecking this checkboxes

When you are ready click Install

SunsetScreen will now install itseft into the Installation folder

After the installation is completed you will see the Installation completed window

Leaving the checkbox On and clicking Finish will start SunsetScreen

After installation SunsetScreen will create desktop shortcut

and Start menu items

When the program is running you will also have Taskbar and tray icons

If this is your fisrst start of SunsetScreen and you have not used other similar softwares before some options may be grayed out and locked. This is because some video card limitations needs to be removed.

Brightness options will be grayed out and Sunset colour can go down to 3300K and up to 120932 K

SunsetScreen default Night Colour is 4100K – Moonlight

The default Day Colour is 6600K – LCD screen “white”

You can change the color temperature also from the Preset dropdown, but if you select value lower than 3300K you will get this message

Lets fix this by Expanding color range. Click the yellow Expand colour range button

User Account control window will open. Now press the Yes button to allow SunsetScreen to make changes to your system and to expand the colour range.

After this you will se this message

Restart your PC to finish the gamma and colors unlocking.

After restart all options will be available.

Now the Sunset colour can go to 500K and up to 9 854 736K

You will probably never need values over 6500K, but still you can go up a lot.

The brightness slider is also available and it can go down to and up to 20% and up to 100%

All presets bellow 3300K will also work

Up until now this was only a basic overview of SunsetScreen. Now let’s look at the program feature by feature.


In this section I will go and explain every feature. Something you need to know about SunsetScreen is that during the day there is one settings and during the night there is another setting.

The 2 blend together with gradual interpolation which happens in the duration of the transition phase and the goal is to have different settings during the day and during the night.

From there on all options and customization are around tweeking the day night or transition values. Some options fix bugs into how Windows has imlemented the gamma api and some things are nice to have like the shortcuts and screen inversion.

Sunrise time

Sunrise time is used by SunsetScreen to determine when the Day Colour will be active. If the Sunrise time is set to 6:00 AM and the Transition phase is 60 min until 5:30 AM the Night Colour settings will be used.

Then from 5:30 AM to 6:30 AM there will be gradual interpolation from night to day colour. To set different Sunrise time you can’t use the keyboard instead you need to use the arrows into the UI.

The left arrows control the hour and the right arrows control the minutes. If you are not familiar with AM and PM you can check the 24h checkbox to see the time into 24 hours format.

Note that when you change the Sunrise time the Sunset time will also automatically change.

Delay until sunset

With Sunrise time you set when the day starts. Combine this with the Dalay until sunset and you will get the sunset time.

With the Delay until sunset you can control when will be the sunset and when the Night colour will be used. SunsetScreen is using the sunrise and sunset time to choose which colour will be used.

If it’s half the transition phase time after sunrise Day Colour will be used. If it’s half the transition phase time after sunset Night Colour will be used.

The maximum value of Delay until sunset is 23 hours. The minimum value is 0.

If the delay is 0 Night color is used all the time day and night.

Transition phase

When it’s time for sunset or sunrise there is gradual interpolation between day and night colour settings.

Well with the Transition phase you can control the duration of this gradual interpolation. There is no up limit of the Transition pahase, but there are some presets.


With the Instant preset the transition will be instant and there will not be any gradual interpolation at all. When it’s time for sunrise or sunset SunsetScreen will instantly switch to the correct color temperature and brightness settings.


Quick transition will set the transition phase to 1 minute. When it’s time for sunrise or sunset SunsetScreen will switch to the correct color temperature and brightness settings gradually for 1 minute.


Medium transition will set the transition phase to 10 minutes. When it’s time for sunrise or sunset SunsetScreen will switch to the correct color temperature and brightness settings gradually for 10 minutes.


Medium transition will set the transition phase to 60 minutes. This is the default value of SunsetScreen. When it’s time for sunrise or sunset SunsetScreen will switch to the correct color temperature and brightness settings gradually for 1 hour.


Medium transition will set the transition phase to 120 minutes. When it’s time for sunrise or sunset SunsetScreen will switch to the correct color temperature and brightness settings gradually for 2 hours.


You can also set the transtion phase by hand by writing the minutes into the transition phase input box.

The minimum value is 0 or the Instant transition. There isn’t maximum value as I tried to enter really big numbers with 50 or more digits.

Send window to tray

Send window to tray will send SunsetScreen to the taskbar tray. Clicking this or the X button actually does the same thing.

In order to Exit SunsetScreen you must click the Exit button or right click the tray icon and click Close program.

Load on Win startup

Load on Win startup will cause SunsetScreen to start when you start your PC. In more details it will just create new record into the Regedit Run path

You can also disable SunsetScreen starting on startup from the Windows 10 Task Manager


Clicking Help will open the the official SunsetScreen documentation available at:


Clicking About will show you information about the program.

What version of the program you have installed. Where it’s installed and the User path for the saved settings which you can edit by hand if you want.


Reset will reset all settings to factory defaults

It will set the Day Colour to 6600K – LCD screen ‘white’, the Night Colour to 4100 – Moonlight, Sunrise time to 6:00 AM, Delay until sunset to 12 hours, Transition phase to 60 mins and all other default settings.


While clicking the X button will not quit the program, clicking the Exit button will quit the SunsetScreen program altogether. Your screen colors will be reset to defaults and the blue light will not be reduced.


With the Running checkbox you can turn SunsetScreen On and Off without quitting the program. When the checkbox is checked SunsetScreen will work, when unchecked SunsetScreen will reset the colors and don’t change the colors anymore.

Night Colour

You can control the Night Colour from the Night Colour tab. The Default value for night colour si 4100K – Moonlight and by clicking the Default button you can reset the Night Colour to this value.

There are also other Night presets:

  • 1850K – Candle – 50% brightness
  • 1850K – Candle – 75% brightness
  • 1850K – Candle, sunset/sunrise
  • 2700K – Incandescent light bulb
  • 3300K – Cool Incandescent
  • 4100K – Moonlight
  • 5000K – Horizon daylight
  • 5900K – Sunlight
  • 6500K – Daylight, overcast
  • 6600K – LCD screen ‘white’

The lower the K value the more blue light will be reduced and the better you will sleep. Brightness doesn’t play much role into the sleep, but matching the room brightness to the screen brightness will help your eyes hurt less.

You can also use the sliders to set your own preferred custom values.

Day Colour

You can control the Day Colour from the Day Colour tab. The Default value for day colour si 6600K – LCD screen ‘white’ and by clicking the Default button you can reset the Day Colour to this value.

There are also other Day presets:

  • 5000K – Horizon daylight
  • 5900K – Sunlight
  • 6500K – Daylight, overcast
  • 6600K – LCD screen ‘white’
  • 7500K – Cloudy sky
  • 10000K – Partly cloudy sky
  • 20000K – Deep blue clear sky

The lower the K value the more blue light will be reduced and the better you will sleep. Brightness doesn’t play much role into the sleep, but matching the room brightness to the screen brightness will help your eyes hurt less.

I prefer to use low value for Day Colour also during the day and to try to get more sunlight. Value of 5000K for Day Colour is good for most people.

You can also use the sliders to set your own preferred custom values.

HSB sliders

By clicking the HSB sliders checkbox you can control Hue, Brightness and Saturation of the screen individually for even more customization

For example by setting the Hue to 50 Degrees and Saturation to 100% you can decrease only the blue light of the screen.

Kelvin values decrease also the green light when some users may prefer setting blue light do 0% while maintaining the green spectrum.

More options

By clicking the More options button you will open the SunsetScreen Options window

From here you can set hotkeys and toogle some for advanced features.


Show defailed info

By clicking the Show detailed info checkbox you will see much more information on the SunsetScreen main window

Check for screen interruption

Windows has some bugs into the gamma api and when you unlock your screen you may lose your gamma changes. If you try to set the same value it will think that it’s already set and your screen will be bright.

Well by small change in the gamma every few seconds SunsetScreen can always preserve your Day and Night Colours even if you lock and unlock your PC.

By default SunsetScreen will perform this every 5 seconds, but you can change this to be faster or slower from the Every checkbox. This check for screen interruption will cause some lag in some games.

Invert colours (night-time mode)

Invert colours will invert all screen colours to their opposite. It will make the white black and the black white like this

This mode is usefull if you want black theme on some application which don’t support black themes.

Invert day/night mode

Clicking Invert day/night mode will cause SunsetScreen to use Night colour during the day and Day colour during the night. This is also usefull if you want to have something like 2 presets and quickly switch between them.

Combine it with the shortcut for day/night mode inversion and you have really fast way to switch between the 2 modes.

Hide main window on manual start

By default when you double click the Desktop icon of SunsetScreen it will also open the main settings window.

By clicking Hide main window on manual start clicking the Desktop, Start menu or the Quick Launch icons will start SunsetScreen minimized into the tray.

Global Hotkeys

You can set keyboard shortcuts for some of the SunsetScreen features from the Global Hotkeys menu. If the shortcut is grayed out click the checkbox of the right of it to Enable it.

You can enable and disable the different hotkeys by clicking the checkboxes on the right

To change the shortcut for some feature, click the hotkey input box and press other key combination like this

Turn SunsetScreen on/off

This hotkey will turn SunsetScreen presing this hotkey is basically the same as clicking the Running checkbox

Decrease brightness

Decrease brightness will decrease the master brightness. You can see the master brightness from the detailed info. This is something like instead of 100% maximum value to be lower or highter and the slider to be relative to this master value.

Increase brightness

Increase brightness will increase the master brightness. You can see the master brightness from the detailed info. This is something like instead of 100% maximum value to be lower or highter and the slider to be relative to this master value.

Show / hide main window

This hotkey will show and hide the main window instead of clicking the tray icon to open it.

Invert colours

Will invert the colours of the screen. This is the same as clicking the Invert colours checkbox

Invert day/night mode


Will invert the day and night mode of SunsetScreen. This is the same as clicking the Invert day/night checkbox


On the right part of the SunsetScreen main window you will see some detailed info about what is happening with your screen right now.

If the Show detailed info checkbox from the options is checked you will also see detailed info at the bottom of the screen.

First you will the language of the app and that FLE Standard Time is used. You will also see the exact hours for Sunrise and Sunset.

Night colour and Day colour are shown as RGB combinations and also the current colour of the screen.

Finally you will see the value of the Master brightness which can be changed by the shortcuts. This value doesn’t depend on the Brightness slider.

Tray icon

You can see the SunsetScreen tray icon in the bottom right corner of the screen

By right clicking it you will get this menu

From this menu you can show the program main screen, exit SunsetScreen and turning on and off fast by clicking Turn off item of the menu.


SunsetScreen config file is located in


You can see it by opening the SunsetScreenPrefs.txt file


SunsetScreen installation folder simply contains SunsetScreen.exe and SunsetScreen.exe.config

SunsetScreen.exe is the file that actually starts SunsetScreen. It depends on .NET framework so if you get some kind of error install .NET framework on your machine.


SunsetScreen is not saving it settings to regedit and doesn’t use it much. The only changes SunsetScreen will make to the registry are the color range expanding and item into Startup key hierarchy.



To install SunsetScreen go to Add or Remove programs

From there find the SunsetScreen item and click uninstall

The uninstaller will try to open. Allow it by clicking Yes

The uninstaller will now ask you for confirmation. If you really want to remove SunsetScreen click Yes

You will wait a couple of settings and SunsetScreen is now removed from your system

Official documentation

Whether you’re a morning lark or night owl, SunsetScreen allows you to set the time of the sunset and sunrise, so you can have full control over your sleep cycle.

SunsetScreen is a free Windows app (for personal use) which helps take the glare off your your screen in the evening.

Scientific research has shown that melatonin – the chemical the brain makes late in the day – is reduced when exposed to blue light.

By tempering this blue light, it becomes easier to wind down properly at night, and thus have a more restful sleep.


Background and motivation behind SunsetScreen.

In the evening and at night, computer screens are starkly blue compared to the ‘natural’ orange glow provided by indoor lighting. With SunsetScreen, it’s easy to dim our screens to an orange-ey hue to match the colour of the indoor lighting we use.

Additionally, scientific research has found that along with over-bright indoor lighting, over-bright screens can affect the production of melatonin – the chemical which helps us to turn off at night to get a restful sleep.

Programs such as F.lux partially solve the problem, but in the winter, I found the sunsets came too early. This caused F.lux to darken the screen early too.

Just because it’s dark outside early, that does not mean the human body clock revolves around the winter’s schedule.

Many, perhaps most people find considerable benefit to extra light during the day during the darker seasons, and if this extends to your laptop, tablet or computer screen, then we should allow that!

Morning larks, night owls and even those who work night shifts will benefit from using SunsetScreen because their sleep cycles are hours apart from each other.

SunsetScreen can be tailored so you can set the sunset and sunrise times appropriately to match your sleep rhythm.

We should also be able to define the colour of the filter by hue, saturation or brightness if need be.

This way, we can match the colour more precisely to the illumination by the light bulbs we have in our houses.

Although dimming the amount of blue light is most important, the overall brightness may also be dimmed too if you so wish.


  • Set the sunset time precisely.
  • Set the sunrise time too.
  • Choose by colour temperature or by HSB for a precise colour.
  • Transition from one phase to the other gradually.
  • Automatically resides in the tray so it keeps out of your way.
  • Loads automatically at Windows startup if you wish.
  • Instantly turn off SunsetScreen if you need to do colour sensitive work.
  • Choose from a range of presets, and reset to default if things go wonky.
  • Small, fast, elegant and easy to use interface in less than a megabyte.
  • Isn’t patent pending unlike something beginning with ‘F’ 😉

SunsetScreen Changelog:

2016-08-28: v1.25

Fixed fading issue on last day of each month.

2016-06-10: v1.24

Added invert day/night mode and fixed display of “Expand colour range” if already expanded.

2015-08-21: v1.23

Windows 10 compatible, and new ‘Hide on manual start’ option.

2015-07-09: v1.22

New ‘Invert colours’ mode – perfect if you need the darkest screen possible.

2015-06-16: v1.21

Fixes memory error message on some systems if you tried to log off Windows and on again.

2015-05-06: v1.20

On some systems, the colour of the screen would return to normal white after a UAC prompt, or PC unlock occurred. This should now be fixed. SunsetScreen should also now have full support for multiple monitors. Extra features include new and improved custom hotkeys functionality, Options window, and numerous tweaks.

2015-03-29: v1.18

Fixed ‘bug’ which may cause a slight, but noticeable flicker for some users. This was originally added to act upon any unforseen changes back to the default screen’s colour from the OS, but affected systems are relatively rare. See the docs though if you find the screen occasionally goes back to default (when it shouldn’t) as you can set the ‘periodicallyUpdateScreen’ parameter to true to bypass this problem.

2015-03-29: v1.17

Fixed bug which may prevent the return to normal screen colours after exiting SunsetScreen. Also added tray menu item to turn SunsetScreen on/off. Finally, because of the maturity of SunsetScreen, by default, “Load on Win startup” is now ticked.

2015-03-28: v1.16

Keyboard shortcut to turn on/off SunsetScreen. Also included masterBrightnessIncrement setting for power users.

2015-03-28: v1.15

Minor GUI tweaks and disabling of keyboard shortcuts until colour range has been expanded to reduce potential confusion.

2015-03-27: v1.14

Added keyboard shortcuts Alt+PageDown and Alt+PageUp to control the brightness independently of the main app’s controls. Also, 4100K Moonlight is the default colour temp on first use now. Reinstalling the app will now automatically close the older version.

2015-03-25: v1.13

Closing the app with the standard close button keeps SunsetScreen active. You can still close the app with the Exit button if you wish.

2015-03-21: v1.12

Thanks to everyone who has helped support SunsetScreen with suggestions and error reports. Bug fixes in this release are: Easily resetting Windows XP is now possible without closing the program first. The button to reset that current colour to default is now called “Default” instead of “Reset” to differentiate it from the main “Reset…” button.

2015-03-20: v1.11

Minor tweaks and fixes. The 12-hour clock format is now default again.

2015-03-20: v1.10

Big bug fix to solve crashing when changing to sunset/sunrise in many countries. Editing a single line of code did the trick. I can also now reproduce the errors on my setup, so if any future errors do crop up (which I doubt), I’ll be onto them in minutes.
Also fixed crash when trying to change the Delay until sunset (which only appeared in 1.05).

2015-03-19: v1.05

Has 24 hour mode option (default) and is more compatible for worldwide usage.

2015-03-18: v1.04

New ‘Info’ checkbox which displays more detailed information should you choose. Also overhauled system for expanding the colour range (until you do, certain options are now greyed out or restricted for sanity’s sake). Finally, colours are more numerically precise.

2015-03-17: v1.03

SunsetScreen now allows you to select ALL colours including darker shades. Simply look for the bright orange button that will appear when you try, click it, then click Yes to the prompt, and then reboot, and voila.
Resetting to factory settings also now doesn’t affect the “Load on Win Startup” setting.

2015-03-17: v1.02

Switched default mode to “Cool Incandescent” whilst I figure out a way to allow Windows 8+ to support darker screen modes.

2015-03-16: v1.01

Preferences are autosaved after controls are changed (before, you needed to manually close SunsetScreen for it to save).
Also fixed bug when occasionally certain Windows prompts may turn the screen back to normal and SunsetScreen didn’t respond afterwards.

2015-03-15: v1.00

First release!

Final thoughts

SunsetScreen is good and free program for blue light reduction for Windows. It will help you sleep better by reducing the amount of blue light emitted from your screen. This will also help your eyes hurt less when you sit in front of the computer late at night.

Thank you very much for reading this article. It’s important for us to try to make digital displays a little more healthy.

Daniel Georgiev – Founder of Iris ?

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