Sleep, and thirst is not a problem, but it is the food supply you have to manage, your character's fullness is based on percentage which means you need food to survive. Otherwise your characters will starve if it runs out. Cooking food is also an important element as it can improve or alter it's properties. Secondly your character's equipment such as weapons and armor also needs to be maintained through repairs to keep it from breaking if it's running out of durability. Time can sometimes lead to common problems such as food spoilage if it runs out of freshness which is also based on percentage. survival elements in this game is not as heavy for as long as you get a hang of it.