Back when I was kid, my family was somewhat poor, but around the time when I was about 10 or so, my father's masonry business started picking up, and my parents bought a beautiful piece of lakeshore property close to our house. Being extremely skilled in all methods of construction, my dad was building a log cabin almost entirely by himself. Over the summer, the foundation was poured, and by winter, the house was beginning to get framed in. I remember I was helping him on the weekends as a gofer, just playing around mostly. That day he was setting up the roof rafters in the lofted section of the cabin, where there was no second floor. He was standing on top rung of a ladder that was balanced on a scaffolding plank that was balanced between two of the first floor rafters. Super OSHA safe.

I can remember hearing a scraping sound as the ladder slid out from under him. He fell backwards and hit the back of his head on one of the first floor rafters, which pushed him forward, and caused him to hit the front of his head on the floor.

I ran over to him, and as far as 10 year old could tell, he looked dead. I was freaking out, until I remembered that he had a bag phone in his truck(this was back in the 90s). As I was crying and screaming to my mom that dad was dead, he got up, brushed himself off, and looked fine! He kept saying, "What happened?" Over and over in a low voice. I told him he fell and hit his head, but he just looked confused and asked what happened...

Finally my mom got there and drove us to the hospital. He had some sort term amnesia from brain swelling, but was otherwise OK. The only long term effect was that he was convinced Reagan was president for a while afterwards.

TL;DR: wear fall protection.