From the Metro interface (this is the one with all the different titles)
Scroll up to the right hand corner to bring up the charm bar
Click Change PC Settings
Click Sign-in Options
Look for Password policy
Under that there is a change button. Click that. It'll change it so that every time the computer goes to sleep, it won't require you to login. I would recommend though having it lock when the screen saver comes on for at least some protection.