I'm a bit tired of setting my screen contrast and brightness manually for each screen every morning and evening, so I'm looking for a way to automate this.

I'm already using F.lux and it's great, but it only changes color temperature. In the night, I still find my screens too bright. Recently I found Screenbright which does exactly what I want, that is, changes hardware brightness and contrast, and works from the command line as well.

Now I'm off to automate this. Is there a way to set Windows task scheduler to trigger task on every sunset and sunrise? I can set it to a fixed time every morning/evening, but that's not as elegant as I want it to be.

  • 1
    No, you would need a program which has the algorithm to calculate the sunrise and sunset times and then you could use those times to set scheduled events for the next 9069 days.
    – Dan D.
    Mar 4, 2013 at 0:07
  • That's not enough- sunrise/set times don't take into consideration the direction the OP's window faces, or if it will be overcast or sunny on any given day. Without an ambient light sensor this is going to be a source of constant frustration. There are far too many variables to accurately predict the brightness in the room based on information from the internet. Mar 4, 2013 at 0:57
  • Instead of changing brightness & contrast settings, inverting screen colors achieves almost an instant 90% drop in brightness. (wiki/Light-on-dark color scheme). And Windows Magnifier is all you need. May 4, 2013 at 13:01

2 Answers 2


Devices are available for USB which are similar to ambient light sensors found on some laptops and TVs. You could possibly write a script which would get values from such a sensor and feed appropriate values to Screenbright, or some similar program that supports command line input. You could then add an item in task scheduler to run this script every hour (or as often as needed) to keep your display comfortable for you.

  • 2
    Exactly. An ambient light sensor would be required. Simply looking at sunrise/sunset times is useless because it does not take into consideration the weather. If it is overcast then the screen brightness will need to be reduced accordingly. The OP needs to measure the ambient light levels himself, not rely on some very basic data from the internet. Mar 4, 2013 at 0:54

I know it's too late to answer this question, but since it's on top result in google then I think it'll help others as well.

There's a program called Sunwait which works properly with Windows Scheduler and you can set a job to run on any events related to sun location.

It needs a bit more digging in case you want to set Theme occasionally

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