Jab, jab, right hook.

‘Eight, nine, ten, you’re out!’

In the blink of an eye, a well-landed punch can send you flying out cold before you even hit the floor. That’s something any professional boxer hopes for — or fears if he happens to be on the wrong end of a punch.

But what happens within the brain when it suffers such trauma?

Blackouts: the brain’s safe mode

The brain is very fragile. It’s almost entirely made out of blood vessels and nerves. We’re talking about a soft, mushy mass of tissue that controls all neural higher functions and commands you as a person. But despite this shortcoming, the brain is remarkably resilient at receiving trauma. ‘Blackouts’ help in this respect, acting like a sort of defense mechanism.

All this mushy mass is floating in a clear, colorless liquid called the cerebrospinal fluid which protects the brain from coming into contact with the skull. If the punch is good enough, it could cause the brain to slam into the skull from the acceleration caused by the blow and the deceleration caused by the muscles and tendons trying to prevent the head from spinning further.

When the brain slams into the skull, you get trauma — brain cells literally start dying from the physical impact. This happens multiple times as the brain bounces off the walls of the skull on and off until the energy from the blow is dissipated.

The trauma causes an overwhelming number of neurotransmitters to fire simultaneously. This behavior induces a form of nervous system overload, causing a system crash in the form of temporary paralysis.

Another mechanism that causes loss of consciousness has to do with how blood flows to the brain. A reflex area in the brain called the sinus regulates the flow of blood and oxygen to the head, but a good knock to the jaw can jolt the sinus. This lightning-fast altering of the blood and oxygen flow can be enough to cause a blackout.

How long before you can recover from a knockout?

It can take anywhere from a couple of seconds to a couple of minutes before a person can regain consciousness — it all depends on the severity of the blow. Some people can shake it off and are only left with a headache. Others that are less fortunate can incur serious medical problems from the concussion, like cerebral bleeding and even death.

The blow from a KO-quality punch often leaves its victims with memory problems, mood changes, confusion, and a slower information processing speed.

If you suffer repeated blows to the head, like athletes in contact sports often do, it’s possible to lose brain volume in the frontal and posterior regions of the brain as white matter dies. Chronic damage such as personality changes and dementia are some of the risks football athletes or boxers face.

A professional boxer’s punch can pack 400 kilograms of force, but you don’t need to hit that hard to knock someone out. Rather, targeting is far more important. That’s because, as outlined earlier, knockouts happen when the brain rotates very fast. Someone could get hurt pretty bad if hit at the top of the head but may not fall unconscious. The same blow to the chin or side of the jaw area is a different matter.

If you’re unfortunate enough to suffer a concussion, either after a fight or an accident, the best medicine is rest. If the headaches don’t stop after a couple of days, visit a doctor immediately.