An old classmate once suggested that I had played too many varsity football games without a helmet.
More than likely, he was jesting. But the hard-shell Riddell helmets we used in the '60s are not much different from the headgear NFL players use today. No cushion, lots of compressed air on impact and the false sense that, helmeted, one could run headfirst into a brick wall.
From Midget League through college, I was lucky never to have been knocked cold on a football field, but I got my "bell rung" countless times. In every case, a headfirst tackle caused me to see tinsel rainbows and hear television jingles. I always thought a concussion required one to leave the field woozy or worse. I never realized until today that those optical and aural effects were signs of concussions.