Pandiculation

It's Friday and you just got home from school. You stayed up until 1:00 working on your essay for English, and you're completely exhausted. Your getting ready to go up to your room to take a nap, when you hear your mom calling your name. Your brother is sick with a cold, and she needs you to go to the hospital to pick up some medicine for him. You can't seem to stop yawning due to how tired you are, but you know you have to do it for your little brother so he gets better. You leave the house at 1:30, and get to the hospital at 2:00. You still can't stop yawning... when you arrive at the hospital at 2:00, you're in line for the medicine, and you realize people around you are starting to yawn. Soon the whole hospital is yawing and 30 minutes later the doctors are dragging you into containment. They shove you into a plastic quarantine as you try to scream, but you're yawning. After a while in containment, you realize there is a back door to containment, and that there is a 4 digit lock hanging off it. Now if you could just figure out the combination...