How can I send power on/off signals to a VGA monitor?

How can I send power on/off signals to a VGA monitor?

I've used some old spare parts to make a sort-of kiosk for my kitchen.
It's running OpenBSD and has a simple text based UI (no X Server).
I plan to add an Arduino with a motion sensor that communicates over
serial port to my app so that if there is any motion the monitor will turn
on and display the time and weather and after a period of no activity it
will turn off.
I would like to know if this is possible to do in software before I have
to take the monitor apart and create a hardware solution (emulate pressing
the power button with an opto-isolator or transistor or hacking up the VGA
cable).
I have a feeling this is possible because power-management software seems
to be capable of doing so but I am not sure how to go about it.