This has been going on for three days now
Because the natural clock in your brain for some reason thinks there's something important happening at 4. Creation alone can describe why this happens. I went through a phase in my adolescent years when I woke up at 3:20am every morning. Nothing happened, I thought I was an insomniac... :D
I always wake up at before my alarm clock goes off. its so annoying cuz i wanna get that extra 30 mins of sleep. But i just have a natural alarm clock lol
If you think you are going to wake up at four than you will if you dont than you probably wont, it might be because of stress that it started though
You are creating a habit and your subconscious is now aware that is troubling you. So now since you expect it will happen then it happens.