You woke up at the wrong time in your sleep cycle. PM me for additional information.
did you sleep soundly? Where you more tired than usual? Is 7 hours sleep usually enough? Have you been drinking, having drugs ? Have you changed your diet recently? Are you sick?
Maybe need some vitamin B.
You have sleep apnea
because your body recognizes the odd sleeping schedule and that's its natural response mechanism.
Need to sleep at least 8 hours per day :)
that's why you feel tired, you got a reason ;p