I have noticed this for the past two nights. Last night I tried to go to sleep earlier than the night before and I still woke up late. I slept for about 10-11 hours each of those nights. I felt very groggy, still tired and I had a headache when I woke. I do not know why this. I have been having some trouble falling asleep lately. I also have chronic sinusitis going on and that could be affecting it. I just feel super energetic at night. I am about to go try to wind down with a book.