We shut down all the computers (and the networked printer) every evening before bed. It's just personal preference really. Well, apart from the printer, because that likes to do some sort of cleaning routine that's loud enough to wake you up should it do it in the middle of the night. With 2 toddlers in the house, we'd rather not wake them up 
Sleep works just as well though, don't worry about it.
Sleep works just as well though, don't worry about it.