[Georgio]

Код:

@echo off

for /f "tokens=1,2 delims=:" %%i in ("%time: =0%") do (
    if "%%i%%j" lss "0800" (nircmd setbrightness 3) else (
        if "%%i%%j" lss "1900" (nircmd setbrightness 100) else (
            if "%%i%%j" lss "2300" (nircmd setbrightness 60) else (
                nircmd setbrightness 3
            )
        )
    )
)

exit /b