Hi,
Please read the following:
Sleep: Keeps your session in memory and puts the computer in low-power state so that you can quickly resume working.
Hibernate: Saves your session and turns off your computer. When you turn on the computer, Windows restores your session.
From your post it seems you put your computer on sleep while you're sleeping at night, hence you're not in need for it all the night. Thus I suggest you to use Hibernation property. Note that for 1 GB of RAM you have, hibernation will require 1 GB free storage to be able to save session in a file for fast resume.
Good luck 