How long could you sleep?

If I fall asleep, I am guaranteed 10 hours of sleep, at least. And that's even when I don't want to sleep that long. The longest I've ever done is 20 hours, and that was just after staying up one night. I've never tried staying up two nights in a row, I imagine I would not awake for quite some time if I did.

Waking up is not a fun thing for me to do. It is next to impossible for me to actually wake up in under ten hours. The only proven method so far seems to be someone hitting me over and over. Once, when I lived in the dorms, I woke up and there was broken glass on my desk. I asked my roommate what happened, and he said when my alarm went off, I hopped out of bed with my eyes closed, ran to my desk, waved my arms at everything until the alarm went off, then ran back into bed. I had no memory of it, as I was still asleep. I've also apparently just slept through the sound of my alarm entirely (and I own one of those extra-loud ones). I miss tons of class because of this, and have accidentally slept through three exams in as many years of college because I went to bed within ten hours of when I was supposed to get up.

Jam it back in, in the dark.