This is already a creepy picture, isn't it? It looks like a photoshopped picture that just got duplicated over and over on top of each other. As you look closer everyone is obviously different, but if you look through hazy drunk eyes like me, it looks a little weird. That's why this yawning soldier stands out even more. In a world of uniformity, he's doing his own thing: being really tired.
You have to wake up at 5am at the minimum in the military (I'm assuming based off of movies and TV). No wonder this guy is tired, and when a yawn comes, it's not like you can just stop it. You have to ride that yawn out. Your commander could be right in front of you and you'd still have no choice but to rip a loud yawn.