Excessive yawning???

Okay on my way back from class today I yawned like 45 times in like less than 15 minuates and these weren't half yawns these were I'm going to fall asleep if I don't yawns. I try to sleep normally 10 to 7ish but i have been hospitalized lately for a number of health issues. is this normal of could this be a sign of somethng else? it has been happening more often lately