I don't know how or why that is, but if you figure it out please bottle it up and send me some.

But seriously, it happens to me on and off when I sleep in. Especially if it's in between snoozes on my alarm clock before I gotta go to work. Some times 10 minutes feels like it's been 30, and I have to keep checking the time to make sure I didn't sleep too late. It only happens to me once in a blue moon though.