How to Change Screen Brightness by Time of Day on Windows 10

Windows 10 does not include a built-in schedule for changing a display’s actual backlight at chosen clock times. A practical option is ClickMonitorDDC 7.2, whose timer can run brightness commands such as b 70 at one time and b 30 later. It works only when the app can control the display, and ClickMonitorDDC is an old, unmaintained utility. If you only want warmer colors after dark, Windows Night light has a built-in schedule, but it does not lower the screen’s physical brightness.

Check monitor support and the utility’s status

For an external monitor, look in its on-screen display menu for DDC/CI and turn it on. Menu names vary by manufacturer. The monitor also needs to expose brightness control: Microsoft’s monitor API reports failure when DDC/CI is unsupported, and lists brightness as a separate monitor capability. A laptop panel may work through ClickMonitorDDC’s laptop support, but the available brightness steps depend on the panel.

ClickMonitorDDC’s final version is 7.2. The original developer website is no longer available, and the project repository describes its downloadable files as a community rehost. Its rehosted files and project notes and the copied 7.2 instructions are not an actively maintained official download. Only run an archived utility if you are comfortable verifying its source and file; otherwise use your monitor’s controls. Windows 10 support ended on October 14, 2025, so keep the PC on a supported security-update path when possible.

Set brightness changes for specific times

1. Enable DDC/CI. Use the monitor’s physical buttons to open its settings or system menu, find DDC/CI, and set it to On. If you are using a laptop, first confirm that ClickMonitorDDC recognizes the built-in screen.
2. Start ClickMonitorDDC. If you choose to use version 7.2, extract its archive and run the program. It appears in the notification area near the clock. Open its panel and confirm that the target display is listed and that a manual brightness change works before adding a timer.

3. Open the timer settings. In the utility’s panel, open Settings and select Timer, Transfer, Limits. Under auto-run command-lines, enable a row by checking its box. The 7.2 instructions describe up to eight scheduled command rows.
4. Enter a time and brightness command. Set the time for the row, then type b, a space, and a brightness value from 0 to 100. For example, b 70 sets 70, while b 30 sets 30. These are sample levels, not recommended values for every monitor. Pick levels that remain comfortable and readable in your room.

A simple two-point schedule might look like this:

5. Apply the rows and verify the monitor. Select Apply, then OK. Keep ClickMonitorDDC running in the notification area; closing it prevents its timer from issuing a change. The archived instructions say a scheduled command runs once per day and, when the program starts later in the day, it applies the nearest earlier scheduled command. If you have several displays, test each one: a command without a monitor name targets the utility’s current default display.

If the brightness does not change

• Confirm DDC/CI is enabled, then reopen the utility or rescan monitors. A dock, KVM switch, or adapter may interrupt monitor control.
• Make sure the intended display is selected. ClickMonitorDDC sends an unqualified command to its default monitor, so one row may not affect every screen in a multi-monitor setup.
• Use the b command for brightness. Contrast and blue luminance use different commands and change different display properties.
• Remember that a timed command is a step change, not a smooth transition. If the computer is asleep or the app is closed at the trigger time, the display cannot be adjusted at that moment.

Brightness versus Night light

To schedule a warmer-looking screen instead, go to Start > Settings > System > Display > Night light settings, turn on Schedule night light, and choose Set hours. Microsoft describes Night light as a warmer color treatment; it is different from changing the backlight level. Its brightness and Night light instructions are in Microsoft’s Windows display guide. For DDC/CI capability details, see Microsoft Learn’s monitor capability reference; for Windows 10’s support status, see Microsoft Support.