Alfred didn't wake up in the middle of the night, and he absolutely did not wake up feeling incredibly hungry. He didn't even start to think about the leftover cake that he may have seen Ms. Patmore hide away in the larder earlier that day, and he did not promptly leave his room and sneak downstairs to eat it.
And if any of this had seemed like it was happening, well, it must've been because it was all just a dream. Dreams are tricky things, they are. Especially lucid ones. Alfred knew that although he might've been, at the moment, dreaming that he was eating a slice of chocolate cake in the kitchen, that in reality, he was still up in his room, fast asleep.
Unfortunately, it wasn't turning out to be a very good dream. The cake was stale and crumbly, and all Alfred could find to wash it down was a bit of cold tea left in an abandoned teacup on the table. He didn't know whose tea it had been previously, but why should that matter in a dream? Next to where he'd found the cup, was what looked like an unfinished card game. He shrugged at the mess of cards (Mr. Carson'd pitch a right fit at that, he thought absently), and wandered back towards the doorway.
That was when the auditory hallucinations began to set in. So when Alfred had cautiously peered out into the hallway, because he'd thought he'd heard something coming from the vicinity of the staff coat room, he knew that he was merely imagining it. What sounded like muffled moans and the slapping of skin against skin was really nothing at all to worry about. Perhaps it was brought on by the sound of a branch brushing against Alfred's window as he slept. Or the sound of his stomach gurgling. Or a barn owl flapping around outside. (Well, he didn't know about that last one.)
Building up the nerve to peek inside the coat room, he knew couldn't possibly be seeing...what he was seeing. He saw what looked like a mostly clothed Mr. Barrow pinning a notably less-clothed Jimmy up against the coat-lined wall, buggering him senseless. That clearly wouldn't ever be happening in real life, and Jimmy probably wouldn't have been begging him, in the hushed, desperate tones that he was, to do it harder, and faster, Thomas, oh god, yes. Realistically, Jimmy wouldn't be saying those things, Alfred reasoned to himself. Because Jimmy didn't like Mr. Barrow like that, and anyway he would probably be doing the buggering if he did, and, Alfred was going to stop that train of thought right there.
Of course, if it hadn't all been a dream (which it was, he knew it was by now)- Alfred certainly would have dropped his cake in shocked, moral outrage, rather than proceeding to shove the rest of it in his mouth. He would have cried out in anger, and swiftly ran to ring the police, instead of standing there dumbly, chewing and staring, unblinkingly, at two men committing an unspeakable act against what he was sure was Ms. Hughes' best coat.
Since all of this was assuredly not happening, he simply yawned heavily, turned away, and slunk back upstairs to bed.
Alfred woke up the following morning with a stomach ache. There was chocolate smeared on the corner of his upper lip, and a multitude of cake crumbs clinging to the collar of his undershirt. He decided not to think about what that meant. He also decided that perhaps he ought to go into town soon, and see about getting his coat cleaned. Just in case it maybe needed it.