... dim the screen (boss-key)
CTRL + Windows key + F10 to change brightness to maximum
There is also possible to set initial value of brightness when starting the program, just add argument in percent (without % sign). This example will dim your brightness at 30%:
nightmode.exe 30
This program is free for personal & commercial use.
It works on all Windows XP and higher (2k/2003/Vista/2008/7/8/8.1/10) both in 32-bit and 64-bit editions.
It may require .NET 4.0 framework.