screen brightness changing

Question

screen brightness changing

Micky Farber 0

my screen brightness changes every 20 seconds. the light in my room has not changed. i can't figure out how to stop it. I've tried looking at the brightness in settings etc. nothing seems to get it to just stay bright. ??? please help!!

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2 answers

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Answer 1

David-M 127.3K Independent Advisor

Hi. I'm David, and I'm happy to help you.

To be able to assist you better, please clarify the following:

Does the brightness change with a completely static image on the screen, or only when you switch between light and dark windows?
If it is a laptop, does this behavior persist when the device is plugged into a charger?

Also, please share a screenshot of your system information.

Press "Windows + R", type msinfo32 and press Enter.

Maximize the window and use the shortcut "Windows + Shift + S" to use the screenshot tool.

Looking forward to your reply.

Micky Farber 0 Reputation points

2026-09-22T00:16:05.31+00:00

hi It is not a laptop. It changes with a completely static screen.
Micky Farber 0 Reputation points

2026-09-22T00:16:57.1+00:00

when i hit win+ my entire screen gets so large you can barely see anything. Then i have to ctrl alt delete and log out.
Micky Farber 0 Reputation points

2026-09-22T00:17:52.09+00:00

ALso i dont have a brightness slider. I dont really even have a brightness adjuster. I tried uninstalling my device drives and reinstalling it. that didn't help either.
David-M 127.3K Reputation points Independent Advisor

2026-09-22T12:46:16.1666667+00:00
Sorry for the delay in reply. I've been offline.

Thanks for the clarifications.

About the screen getting huge: Based on the behavior you mentioned, you enabled the Windows Magnifier (Zoom) tool, which is usually enabled by pressing the "Windows" key and the "+" key together. If this happens again, you can turn it off by pressing "Windows" and "Esc" together.

About the brightness:

Is your computer a traditional Desktop PC with a separate monitor, or is it an All-in-One (where the computer components are built directly into the screen)?

Also, please share a screenshot of your system information. I might need this to determine if you require a specific driver, in case it's an All-in-One.

Press "Windows + R", type msinfo32 and press Enter.

Maximize the window and use the shortcut "Windows + Shift + S" to use the screenshot tool.

Looking forward to your reply.

Answer 2

If the brightness changes even though the room lighting has not changed, the most likely causes are automatic brightness based on ambient light or content adaptive brightness control.

Try these in order:

Open Start > Settings > System > Display.
Under Brightness, turn off brightness automatically when lighting changes if that option appears.
In the same Brightness area, look for Change brightness based on content and set it to Off.
- This feature can dim or brighten the screen depending on what is on the display, even when the brightness percentage looks unchanged.
- Turning it off can reduce battery life.
If the device is a Surface, this behavior is normal for adaptive brightness and contrast. In Settings > System > Display > Brightness, set Change brightness based on content to Off.
If the brightness slider is missing or does not work, update the display driver:
- Open Device Manager
- Expand Display adapters
- Right-click the display adapter
- Select Update driver
If this is a desktop PC with an external monitor, Windows may not control brightness. Use the monitor’s physical buttons instead.

If the screen is changing every ~20 seconds, also check Start > Settings > System > Power & battery > Energy recommendations and see whether either of these is applied:

Save power by screen contrast and brightness for the content shown
Change brightness automatically when lighting around me changes

Those settings can cause repeated brightness adjustments.