Method 3: Disable Automatic Brightness Level Change Restarting the device may just magically solve the display is automatically dimming to lower brightness issue on waking up from sleep. Sometimes, the Windows 10 operating system may just behave erratically if it’s not resting (shutdown) for a long time. Note that manually adjust brightness level if display is dimmed after waking up is temporary remedy, as the issue likely to persist on next wake up. Brightness level in Windows 10 can be changed easily through Settings (in System -> Display), or through the slider at the bottom of expanded quick actions section of action center (notification pane at the right side of Taskbar). The immediate fix the screen display dim issue after waking up is by adjusting the brightness up manually. Method 1: Manually Adjust the Brightness Level Bar While the reason on why unexpected screen brightness dim happened is unclear, and may probably related to power savings (lower brightness saves power), here’s a few steps that you can take in order to resolve the issue. The issue happens even though the settings within the active power plan does not offer the option to change display brightness option, or is configured to only change display brightness only when the device changes between on AC power or battery power.

Upon checking, brightness level of the device is automatically reduced, sometimes more than 50% which makes the screen much darker. After a Windows 10 computer wakes up from sleep mode or sometimes from hibernate mode, the display appears to be dimmer than usual.

Screen darker after windows 10 update