I was already under so much stress from work that I had part of my intestines bind up for a week, the doctors couldn't figure out what was wrong with me so they decided to give me predinsone... I felt sick so I went home on a Saturday, after 'only' hitting 50 hours for the week. My boss called to yell at me and tell me to come back to work, the next thing I clearly remember was being in a hospital.
I still had to work for that POS for 2 years after that happened. For a long time I blamed myself, until a year and half later when my mother was within an inch of life in the hospital and I wanted to leave early and see her, he said "Didn't I already give you a day off for that?"
As for what kind of person that is? Narccists. And they can be very damaging to their employees if they aren't rooted out from management quickly.