Hello, I woke up really early today fully awake, around 5:15am. However, feeling that it was too early and taboo to be up at this time (especially on a saturday), I went back to sleep and woke up again at 8:20 am, but this time feeling very tired and groggy, not wanting to get out of bed. I am curious, how is it that I can sleep another 3 hours, yet feel completely tired, when I was lacking that 3 hours I was perfectly awake. Yet most days of the week, I wake up at 6:15am with an alarm clock and also have that groggy feeling. Is an irregular sleep pattern the cause of the groginess? I should mention I will go to sleep from 10-11pm, so all the times I am talking about have roughly the same starting hour of going to sleep.