Why do you wake up at 3 in the morning and what you can do to fall asleep again. A nightmare that stalks us, every night, to break our sleep and torpedo us with everything that worries us.
"Because... our brain interprets that we have already slept enough so that nothing bad happens to us." And, here comes the most 'bad' part of the matter, "it considers that the time has come to pay attention to all our pending issues again and, therefore, it 'bombards' us with a lot of worrying thoughts"