October 28, 2012, 3:07 PM — Here's how you can make sleep mode the default shutdown option in Windows 8.
1. Open the Search charm.
2. Type in Power.
3. Tap or click on Settings.
4. Click or tap on Power Options.
5. If you are on a desktop or tablet system:
Click on "Choose what the power button does," then select Sleep, then tap or click on Save Changes.
6. If you on a laptop:
Tap or click "Choose what closing the lid does." Then, next to "When I close the lid", make your selection for what you want your laptop to do on batter or plugged in power. Then click or tap Save Changes.
For more, see the original article at the link below.
Windows 8 Tips | Microsoft