Concussions can have many side-effects other than headache, including loss of balance, amnesia and irritability. They also can change sleep patterns drastically.
They also aren't caused just by blows to the head. Severe blows to any part of the body can also be a cause. Shooting a hard-kicking rifle or shotgun obviously causes a serious bloe to our shoulder, which is closely connected to our neck and head, and the firearm may also whack our cheek pretty hard.
Sometimes concussions don't even result in immediate symptoms, whether headache or others. Repeated concussions can eventually cause permanent symptoms, even if they're not severe, the reason that boxers often show all sorts of symptoms. It's also the reason that there's been a lot more concern about football players in recent years, especially kids.
Repeated concussions ain't something to mess with, one reason I have started shooting lighter-recoiling guns in recent years, and shoot my bigger ones only when necessary AND when protected as much as possible.
