Automatically Dim Your PC Screen In The Evening


If you use a Windows PC at home, whether desktop or laptop, you probably use it throughout the daytime and into the evening.  While the screen brightness you configure for use during the daytime is probably just fine, there's also a good chance that it's too bright for the evening, when ambient lighting (ie, around you) is much dimmer and of a different "colour temperature".  That is to say, it's probably more yellowy and less bluey.  Which means that, when you do finally go to bed, the additional blue light you've been seeing during the evening could keep you awake and prevent you from sleeping as soundly as you might otherwise have done so.

To the rescue of all night-owls comes a program called Sunset Screen.  At pre-determined times (sunset generally, though you can change it), it automatically dims your screen and changes the colour temperature too.  The author claims that the program is preferable to the better-known f.lux utility because the timings are more flexible and because there's a greater range of colours available.

Sunset Screen is free, and the download is less than 1M.  You'll find it at and it's also available as a portable version if you prefer.  The program is malware-free according to VirusTotal and Web of Trust.

If you haven't tried F.lux, and you'd like to experiment with that program too, you'll find details at



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As mentioned in my other post ( see ) when I tried F.lux I found it too reddish for me. I also wasn't happy that it didn't have a portable version. Well, I have been trying SunsetScreen for the past week and I like it. It gives me better control over the colors and there's a portable version that's stealth too. I have also been in contact with the developer and I find he's very responsive - another plus.

Now, I know some people aren't too fond of programs running all the time, but you can easily overcome that by creating a task in Task Scheduler. Configure the task to start SunsetScreen at, say, 35 mins before sunset everyday and you're good to go. You can even add the argument "/hidewindow" (without quotes) to make it start silently in the system tray. In fact, when I raised a query with the developer, it was he who told me about that argument/parameter.

Personally, I've even started to experiment with the "Day" color. If I manage to adjust the color such that it would reduce the daytime strain on my eyes then it would be doubly useful.

It's a keeper so far.

It looks like the developer has joined us.

Welcome Daniel errr... I mean twinbee. It's always nice to see a developer taking such a keen interest in his software. :-)

Hi too, and thanks for the feedback! -Dan

Thanks but no go for me. Win 8.1 Pro x64. Nvidia GeForce GTX 660. f-lux works for years now. This SS just flashes like on/off steadily when run. Rebooted tried some dif settings, no go. Giving Redshift a look tho f-lux prob remain choice (boy is the default white light at night a killer w/o it).

Was the flicker very slight and approx every 10 seconds? If so, this should be fixed for version 1.18. Try again and see what you think.

Thanks! Just tried Portable which seems to be v 1.18 and isn't flickering 3-4x a second like installed one last night, VERY noticeable. Not sure if issue will occur at night but will leave it in place and test it w/ & w/o f-lux active (active at moment). Couldn't use it at all at nite.

Did you have Flux open at the time? Make sure Flux is closed before testing. Was the flickering during the time it said "Transitioning to night" or "Transitioning to day" at the top right? If so, that may not be fixed then for you. If that happens again, please let me know, and then try changing the transition phase to 10 seconds, and see if the problem is lessened or gone.

I tested w/ & w/o f.lux active. No go tonight w/ SS. There is no rapid flickering on/off but there is no light-temp reaction, just the default bright screen of Windows. Thanks for help but easier w/ f.lux.

Thanks for the feedback. I presume you had SS running by ticking the "Running" checkbox. Anyway, feel free to email me if you would like to get it working, or otherwise enjoy using F.lux instead.

is there a linux version? made the switch permantely now few weeks back....but still still struggling a little on a few things.....

thank you!

no cam so using f-lux- wow what a difference.....what is freaking me out a bit though is that u go to the link and it knew my exact location down to the street where i am.....just can't figure how, no personal ID/ info on this machine.....all i can think is the ISP is somehow collaborating with them?

There are options other than blaming your ISP. Most PCs are uniquely identified and their geographics locations are often very precisely identified from information gathered with or without your permission on the Internet. At the highest level, most IP addresses are allocated to organizations (ISPs and the like) so their country and maybe city or region/province are known. Accuracy increases further from more detailed location-aware services. You can even read about specific applications. Firefox web browser is upfront about this in their Firefox FAQ on the same topic.

thanks for that! i had no idea....annoying thing though, I'm using Firefox.....and it does state 'opt in' although i never had done so.......which was why it was bugging me! hopefully solved now.......but folk should be aware they are lying there!

If you haven't opted in then Firefox isn't doing it - I just used them as an example of being more open about what happens if you do. Your issue is much more likely to result from something less obvious, like Google.

too many possibilities to be fully sure i think...

but that option was enabled in firefox, and i have now disabled cdn't have over ridden that surely?

All of these applications share a fatal flaw as far as I'm concerned. None of them could automatically detect full-screen applications (games, movies..etc), so they interfere with their colors. And manually disabling and enabling as a solution is just absurd.

Had this programme working automatically on my old laptop and forgot all about it then bought a new PC with a big monitor 6 months ago and have been struggling with eye strain - even considered replacing the brand new monitor which, no matter how much I played with the brightness, didn't get rid of the problem. Feeling the immediate benefit again (I use it during the day too). Thanks for the email!

I actually have another PC and monitor which I use at work, purely to watch the system that monitors all of the servers I look after. I didn't want it to be overly bright or distracting. By fiddling with the brightness, colour and contrast, I did manage to get the picture to be sufficiently non-bright. But something like F.lux or Sunset Screen is clearly simpler.

Hi, thanks- this has a very user friendly GUI.

I use RedshiftGUI, which allows colour control better than f.lux, and uses half the memory of Sunset Screen.

(Noted Sunset Screen requires .NET 3.5 or higher - I don't think RedshiftGUI does).

RedshiftGUI is also sensitive to geographic location, which you can look up by IP address, which means (hopefully!) the times adjust accordingly.