I learned this week that some months back, a friend of mine in martial arts class got (my wife can stop reading here) a concussion. She hadn't told me before, and hadn't made a big deal out of it. Unfortunately, she didn't make enough of a big deal about it at the time, a very risky course to take.
For privacy reasons, I won't go into all the details, but this friend did get knocked out in class, and didn't go to a doctor (I wasn't there to see this happen; I presume people advised that she should see a doctor). She didn't recognize signs that she had received a concussion in the next couple of days. It wasn't until a couple of weeks later, when she passed out and then went to a hospital, that some tests showed she had gotten a concussion.
I'm very happy that she then took time off from sparring. I'm very concerned that she didn't take care of her injury immediately.
The Mayo Clinic has a discussion of concussions. It notes:
The signs and symptoms of a concussion can be subtle and may not appear immediately. Symptoms can last for days, weeks or longer.
The two most common concussion symptoms are confusion and amnesia. The amnesia, which may or may not be preceded by a loss of consciousness, almost always involves the loss of memory of the impact that caused the concussion.
Other immediate signs and symptoms of a concussion may include:
* Ringing in the ears
* Nausea or vomiting
* Slurred speech
Some symptoms of concussions don't appear until hours or days later. They include:
* Mood and cognitive disturbances
* Sensitivity to light and noise
* Sleep disturbances
In my callow youth, I adeptly knocked myself out by flipping over someone's back on a basketball court--I presume I received a concussion, but it was the last day of basketball camp, it was the 1970s, and I didn't see a doctor. I also saw a friend knocked to the ground in a college softball game, and he lost all short-term memory for about six hours--a very weird experience, and presumably a concussion.
Note that you don't have to be knocked unconscious to get a concussion.
Do me a favor: Go see a doctor if you have any suspicion you might have gotten a concussion.