How do you wake up in the morning?

I have such a hard time waking up all by myself! If I haven't had 8+ hours, someone has to wake me up or else I just don't. Sometimes i'll sleep for like 12 hours! I don't know why! I've been tested for sleep apnea and I don't have it. I have to set like 15 loud alarms on my phone and people will call to try and wake me up, but I still can't! Even if I know it's something important!