What is your operating system?
You can also force to hibernate, it's possible that you have to enable the option from your menu, you can find the procedure online.
There are 2 types of hibernation, classical and hybrid suspension. The second is just like normal stand by, but it also saves date on hard drive in case of power failure. You may need to enable that from power settings (advanced mode).
What did you use?
I tried both mode (I have enabled hybrid suspension and I've tried first without unplugging power cable, and the second unplugging it) but I've returned with the canvas still visible (I've pasted a screenshot, no levels or anything else).