When we’re tired, we are often cranky and unpleasant to be around. It’s not that we don’t get enough sleep on purpose, sometimes it just happens.
Imagine your character out-of-sorts. What does she say and do? How does she treat others? React to what others say?
Picture him at work or at a bar. What happens when someone criticizes something he just completed or bumps into him in the crowd? Does he hurl insults? Come up fighting? Or does he simmer and walk away?
Your task is to write a scene in which your exhausted protagonist mingles with others. First, think of the scene. Then people it with at least two others, possibly co-workers or maybe random strangers. Lastly put things in motion.
Be true to your character’s personality. A shy person most likely will not explode in a loud tirade, but a boisterous individual might.
When you are finished, reread and edit. Add details, dialogue, action.
Have fun with this one.