Do your research: A tap on the head

This is the start of a series intended to help writers who wish to get their facts straight. It will be updated once a month. Follow me on Twitter ( to get notified when a new post comes up.

The infamous tap on the head is arguably the most unrealistic device used to knock someone out, to a degree that even medical professionals who don’t deal in head injuries that often get it wrong. It is so prevalent in movies, shows and books that almost no one bothers to check it for realism.

Obviously there is an interest in doing things right in fiction. Technobabble has fallen out of grace, there are fanfiction out there showing off more research than the early star trek episodes.

But still every action or suspense oriented work of fiction insists on hitting people over the head and having them unconscious for a plot-convenient time ranging from minutes to several hours.

Don’t know what’s wrong with that picture? Then read on. Beware, though. You may want to rewatch your favourite scenes with your heroes fainting, before you inevitably lose your willing suspension of disbelief over the matter.

The short version:

Extended unconsciousness without lasting damage is impossible. Instead focus on confusion and disorientation experienced during a concussion, which does the same thing – incapacitate the character – without breaking willing suspension of disbelief.

The Scenario:


Everyone knows a scene like this. Our hero, let’s call him Gustav, sneaks past enemy ranks, a plan to halt the Big Bad’s plan firmly in place. Since the audience knows about the plan, it is destined to go wrong. And sure enough there’s the Dragon right behind him. He hits Gustav hard over the head and everything goes dark.

Cue thirty minutes later, Gustav is neatly tied up, two hundred kilometres away on his way to a Siberian Gulag. He, after momentary disorientation lasting about ten seconds, promptly proceeds to break out of his bindings and the plot goes on.3812840962_cb3d19d492_z


The Science:

Let’s take a look at what really would have happened, shall we?

Let’s jump to the point where the Dragon attempts to knock Gustav unconscious. Obviously the Big Bad wants him to remain alive, otherwise he could have simply told the Dragon to shoot him. Which puts the Dragon in a tight spot, since any knock on the head the sufficient enough to cause unconsciousness is also sufficient enough to cause death.

See, the brain is sort of prissy about the space it occupies. Something as small as a single raptured blood vessel can cause the pressure inside the head to rise to fatal levels.

So, if your virgin-sacrificing, kitten-eating boss told you to incapacitate his nemesis but keep him alive, would you resort to a way that had only a fifty-fifty chance of Gustav surviving?

But let’s say the Dragon is willing to take that chance.

The probability of fatal brain hemorrhages happening is lowest with young, healthy people who ideally diet and exercise. Which applies to a reasonable portion of heroes, so let’s assume the Dragon indeed only knocked Gustav unconscious and no brain damage has incurred.

He will now proceed to drag Gustav through the base of operations, tie him up and put him on that train to Siberia. That process takes him thirty minutes, give or take. If Gustav has not woken up in that time, chances are, he won’t at all. And if he does, he may be safely categorised as a vegetable.

That’s not a matter of chance anymore. Gustav can safely fall unconscious for up to a minute, though in almost all cases unconsciousness lasts way shorter than that.

Anything that goes beyond that means brain damage. Period.

Here’s where even medically trained personnel get it wrong. Paramedics, nurses and doctors technically learn about this stuff. But they also watch TV. If they aren’t confronted with head injuries all that often, chances are they simply forget. (The same goes for those websites that attempt to enlighten you about medical matters. Six out of ten will state that people can be totally unresponsive for up to thirty minutes. That’s advice that can quickly get dangerous.)

But back to topic. Unconsciousness lasting for longer than three minutes is a symptom of brain damage. That doesn’t apply however, if Gustav can be woken up by, say, screaming loudly in his ear or slapping him a bit. If he can, that just means he went to sleep after being knocked out.

However, if he couldn’t be woken up by getting dragged around the floor, aggressively tied up and probably thrown around a bit in the train, then it’s a deep coma.

The kind you miraculously wake up from thirty years later or, well, not at all. It is almost always the kind that has you breathing with the help of a machine.

But, short-time comas do happen. Say Gustav got lucky (considerably) lucky and he indeed woke up from his plot-convenient coma after thirty short minutes rather than thirty years.

Remember what I said about the brain-damage?

If you swapped out Gustav’s brain with mashed potatoes at this very moment, his cerebral functions would actually improve.

We don’t talk about silly concussions here anymore. This is way out of the area of dizziness and a bit of nausea a head injury induces if it feels generous.

We’re talking about complete or partial loss of motor control. He may be able to spasm around a bit but anything more delicate than waving is out of the picture. Forever if not brough to medical rehab.

Speaking? Good luck with that. Moans and slobbers might be in.

And that’s even if Gustav is still aware of himself and his surroundings. Chances are he won’t be able to tell the difference between squares and circles, much less concoct a genius plan to escape from a moving train.

Think 90 year-old in the end stages of Alzheimer’s and you have a rough picture of what Gustav looks like right about now.

The guys in the Gulag won’t have any use for him despite maybe as fertiliser.

So that’s the fate of every character in fiction ever hit on the head for a bout of plot-convenient unconsciousness if reality suddenly decided to kick in.

For a world that puts pain-staking research in how dragons technically could exist, fly and vomit fire, that’s stretching the boundaries of Artistic License.

The Alternative:



What then do you do if you need your Gustav put on a train to Siberia?

I mentioned earlier that a knock on the head always comes with the risk of hemorrhage, but that risk is lowest with young and healthy brains. It is also not too much of a stretch to say Gustav would come out without his brain bleeding itself to death.

Say the Dragon did give him a firm tap on the head to incapacitate him. Gustav does not need to automatically lose consciousness to be eligible for an involuntary train ride.

A concussion comes with a variety of symptoms that even by themselves do not put you in a position to put up much of a fight.

Here’s a list of symptoms ordered from most to least likely. Not all of them need to turn up everytime:

(I haven’t added the short-time unconsciousness, since that has gotten enough coverage just now)


That’s the main reason even a relatively harmless concussion is not at all a walk in the park. Gustav’s head will hurt like a bitch. Characters with a military background will have received training that allow them to ignore a fair measure of pain. They could theoretically keep fighting, especially if there’s enough adrenaline to block out the pain temporarily. But an Average Joe like Gustav is in no position to do much of anything except maybe lying down and pleading for an aspirin.

Short-time memory loss

This mostly means that Gustav won’t remember being hit on the head. It can be more extensive, reaching back hours, days or even weeks. More rarely it affects not recentness of memories but is more theme-oriented. Aka not remembering your name or address, but being perfectly capable to tell how you got where you are.

Fun fact: There is such a thing as anterograde amnesia. I first witnessed it with a patient who got into a bar fight and got hit on the head. According to the paramedics he seemed perfectly oriented, made small talk, cracked jokes.

However, when they arrived at the hospital my colleague asked him if he knew how he got here. He had no idea. From the moment he got hit to the moment he arrived at the hospital he had no memory whatsoever, despite being conscious and aware of his surroundings. This is called anterograde amnesia and it means essentially that for a time the concussed person is unable to store new memories.

After having him checked up and assigned a room he prompty fell asleep (contrary to popular belief you are allowed to sleep with a concussion) but we woke him every few hours to check. The first time I woke him like this he was quite confused as to how he got there, seeing as the last thing he remembered was getting into an argument at a bar. He hadn’t been unconscious for the time but to him it was like he had been.

Confusion or disorientation

The clichéd expression of “Where am I?” has some merit after all. But usually not because of an actual change in location but rather an inability to comprehend said surrounding as familiar. It’s an almost sure-fire way to tell if a person’s got a concussion. If talked to the concussed person may only register about half what is said, which is why it is so important to speak slowly and in simple terms. Having trouble paying attention is also a sign of this. So instead of focusing on escaping the Dragon who is in the process of putting him on the train, Gustav might well be distracted by the shiny buttons on the Dragon’s uniform.

Dizziness/Blurry Vision/Ear ringing

Here’s the source of “How many fingers am I holding up”. Seeing double, triple or quadruple only adds to the fun of the general disorientation mentioned above. Imagine you don’t know where you are and that place keeps multiplying. Not enough? Have a nice, obnoxious tinnitus for good measure. Still not enough? How about feeling as if you are about to pass out, with lights or black spots popping up and out. The ear ringing is especially prelavent when hit on the side of the head (aka close to the ears) and typically comes with a loss of balance as well.


With all the symptoms above we have already established that the Dragon could do everything he wanted with Gustav without fearing of getting into a fight. Unless our hero has mastered the art of projectile vomiting, that’s not about to change.

It does not always involve throwing up, but the nausea itself is usually enough to ground even the most unshakable person.

All these symptoms will usually clear up within a few hours, but can (especially in the case of blurry vision and ear ringing) last for up to several weeks.

If confronted with immediate danger the ensuing adrenaline can temporarily suppress some of the symptoms. Gustav will still not be able to win a chess tournament, but should at least be able to moderately defend himself. However, the symptoms will resurface as soon as the perceived danger is gone or exhaustion kicks in.



Other methods of inducing unconsciousness are of course anesthetics. Which is equally risky, if not even more so.

The famous room being gassed:

Almost impossible, since the dose is almost impossible to get right. If it is too small or our hero doesn’t breathe that deeply he might never feel anything more than slight dizziness. If the dose is too high or our hero takes a couple of deep breaths, he might as well drop dead.

Added difficulty when there is more than one person in the room to be gassed. The dose that would be required to send the 250 pound heavy wrestler dreaming will almost certainly kill the 90 pound scientist, while a dose tailored to the latter will leave the former mostly unfazed.

As a liquid or pill:

Easier, though as with all drug-induced sleep the vital signs have to be monitored closely, lest the patient suddenly stops breathing. That is one of the reasons an anaesthesist has to be present for every surgery.

The chloroform-handkerchief:

Impossible. Unless our hero stands still for at least five minutes and calmly inhales the chloroform he won’t even pass out. It also requires being administered after in short intervals to keep the patient unconscious.