iMac does not hibernate anymore after Mavericks installation I used to be able to press the power button on my iMac shortly and send it to hibernation. 

After the update to Mavericks though this ability has disappeared and now only sends it into sleep mode.

What is going on? Help Please!
Try holding down the Control key when you press the power button.

Here's a note from Apple about the new behavior:
OS X Mavericks: Using the power button

And here's a good discussion:
Can I restore pre-Mavericks power key behavior?