LUCKY!!
I have worn a helmet for years and never needed it.
In fact, I have fallen without a helmet when I was faffing about, rambling/climbing down a small cliff and I fell off and landed BADLY on my forehead from about 4 meters (or more, I don't really know, only a rough estimate from a witness).
Blood everywhere, but I was fine, thus proving that there isn't anything important in my head worth protecting in the first place!!
Actually, when I 'landed' (I felt like the pilot of a plane crashing), I was more concerned that the camera I had over my shoulder was ok, and then I started to wonder when it had started to rain.
Turns out it was the blood from my forehead dripping right in front of my eyes!
I made a point of never cleaning the camera, and it was covered in dried blood for quite a long time afterwards (I'm odd like that).