Step 1: In system tray, click the battery icon and select More power options from the panel that pops up.
Step 2: In the power options window, select either “Choose what closing the lid does” or “Choose what the power button does” from the left panel.
Step 3: In the next window, click the blue text that says “Change settings that are currently unavailable”
Step 4: At the bottom of the windows, a new set of options will become available. Check the box next to Hibernate and click Save changes.