I was living on 4-6 hrs sleep a day for many years, and felt fine, until finally a couple of years ago, it caught up to me. I literally couldn't think straight

I was living on 4-6 hrs sleep a day for many years, and felt fine, until finally a couple of years ago, it caught up to me. I literally couldn't think straight, I had terrible headaches, I couldn't learn anything new. At one point, I couldn't remember what I did that afternoon, my mind was a blank. The straw that broke the camel's back was when I couldn't remember which toothbrush was mine. I went to the doctor, and she suspected I had a brain tumor, but thankfully the MRI was negative. I decided maybe I should sleep more, and in the middle of the work day, I left at 2pm, and went home and slept 17 hrs straight. Now, I can't stay up later than 1030pm, and if I get less than 7 hrs sleep I feel horrible.