Why do you wake up in the morning?

You are tired. You fall asleep. And then you wake up. Why?

Maybe you have a new Witcher DLC freshly installed. Probably you need to go to work or take care of your children. Saying your cells need fuel, so you are woken up to eat is an argument. Altogether there is some reason to wake up.
But for our subjective perception of ourselves, we never stop to think that even if a person had absolutely no reason to wake up, he would still wake up. Presuming he or she is a healthy individual.

Does that mean there is an inherent reason to wake up? The argument here would be of course, survival. But let's consider the person is in #thematrix . They still need to sleep. So the conclusion would be in the brain. And many research supports this, that sleep resets the brain*.
But if the brain has it's survival guaranteed there are two possible answers to the original questions. The brain either requires stimulation, or it's the brains instinct to wake up. And in both cases it's our subconscious doing the deciding.

But the funny thing is, you think you are. You go to sleep when you are tired. You wake up, when you feel like it (if you are not forced). We always think it's our choice.
And it's the same with everything.You eat what you like. You do what you want. You fall in love with a girl you like. But is that really us? Is it all really our choice?

• (http://neurosciencenews.com/sleep-brain-reset-6047/)