11 hours at the cinema

The plan was to see three movies and be home about 9 o'clock in the morning. Instead we saw 4 movies and I came home about 11:30.
Now the time is 12:00 and I've been awake for the last 30 hours (minus all the 1-5 minute naps during the last two films and in the buss on the way home)
I would have enjoyed a breakfast at some coffee house or even McDonald's but I decided to come home, sleep a bit and spend the rest of the day studying.
...So why am I still awake?