Ugh one of my roommates used to do that ALL the time, and she was an incredibly deep sleeper... I'd seriously never seen anything like it up until that point. Her alarm was loud and obnoxious and it would go off for the longest time and she wouldn't wake up, so we'd yell out her name, shake her mattress, and she STILL didn't get up. It was bizarre and annoying, and then when she'd finally wake up... she'd hit snooze/set her alarm and the cycle started all over again, ahaha.