DeepSleep hibernates your Mac to save power
If you use DeepSleep’s Hibernation mode instead of putting it to sleep, your Mac won’t use power or its battery at all, and your open applications and files will still be there when you wake it back up.
http://rss.macworld.com/click.phdo?i=eb2e96bc1a7766b56cefdacb4f7845a0