Currently if you sleep and resume with league of legends still on:
a) you disconnect, and can't do anything
b) you have to go to the task manager to close the program because logging off hangs.
What I think should happen, upon sleep you logout to the login screen, and be happy.
© 2013 Riot Games, Inc. All rights reserved. Riot Games, League of Legends and PvP.net are trademarks, services marks, or registered trademarks of Riot Games, Inc.