If
(A) you go to bed near the normal time,
(B) you wake up near the normal time, and
(C) you slept fairly well during that time,
then you will not be tired. If you violate any of (A), (B), or (C) you will most likely be tired. It appears like you violated (B). Welcome to a day of being tired.
Your body is a creature of habit and chemicals are tied to those habits. Break any one and you'll have the wrong chemcial balance.