Whilst I don't use them myself, there are definitely Mods that add Hunger/Thirst to the Game, and some I believe that make you need sleep
Note: I do not use any of these myself, so do not know if these are the "Must Have" Realism Mods; someone else may know if there are newer/better Mods available, these just come from a quick Tes-Nexus Search.
See You Sleep -- Lets you Sleep in Beds
http://www.tesnexus.com/downloads/file.php?id=16005
Real Hunger -- Makes you need to eat
http://www.tesnexus.com/downloads/file.php?id=3927
Hunger and Thirst Survival
http://www.tesnexus.com/downloads/file.php?id=24340
Realistic Fatigue
http://www.tesnexus.com/downloads/file.php?id=10925