Either a mistranslation or a hint that Metal Gear actually takes place in a collective dream-world that's shared by all humanity when we're not conscious. This guy might not actually be trying to shout really loudly that's he's sleepy, or alert guards around him that he 'fell' asleep, but maybe he's actually having a moment of existential epiphany in which he feels asleep despite being awake.
If you were in his situation, wouldn't you then scream it to the heavens in a way that warranted two exclamation marks?
Gamer, Researcher of strange things.
I'm a writer-editor hybrid whose writings on video games, technology and movies can be found across the internet. I've even ventured into the realm of current affairs on occasion but, unable to face reality, have retreated into expatiating on things on screens instead.