I have arthritis in my back and can only sleep on my side(s) for a short time before the pain wakes me up and I roll onto my back (if I roll off my back while sleeping). I'm pretty sure that picking up SBC engine short blocks and putting them in the back of a truck without help is a likely cause. My back constantly hurts
You young guys take careful note of what the old guys did that jacked 'em up, and don't do it! I'm 67, and could potentially live another 30 years with the pain. Not a pleasant prospect.