Overstimulation caused by brain injury

Before you continue reading, we would like to draw your attention to the fact that Team Hersenletsel-uitleg of Braininjury Explanation has been the first to identify the problem of overstimulation (sensory overload, flooding) caused by brain injury, worldwide. They were also the first to describe this problem (in 2013). Now we would like to conclude scientific research on this. Could you please consider to make a donation for this research?

1. Introduction on overstimulation
Overstimulation is common in people who suffer brain injury, whiplash, ME, other neurodegenerative disorders and in people whose pituitary gland is not working properly.
It is an exhausting situation that has a neurological origin and that arises when more information (in the form of stimuli) is received in the brain than it is able to process. A stimulus is information that we get through our senses; seeing, hearing, smelling, tasting, feeling (external stimuli) or through our thoughts or our bodies (internal stimuli).

Also proprioception or position sense / posture sense can get overstimulated*. Proprioception is the ability to perceive the position of our own body and our body parts.
It seems that this information from different sensory cells of balance can also overstimulate the brain. People even indicate that they feel seasick* or 'drunk', as if the balance is disturbed.
Normally all these stimuli are properly processed by our brains. We call this capacity of the brain 'mental capacity.' After brain injury, the processing of stimuli is often disrupted, (sensory hypersensitivity) and sensory and cognitive overload occurs.
This can result in annoying complaints that are often difficult and slow to recover *. Read more about brain fatigue or neurofatigue.


[* source: our questionnaires, consider this as copyright]


2. Where in the brains?
The brain structures involved in overstimulation are all neural structures that pick up a stimulus and process it from sense to cognition (perception, thinking and remembering). That is, from start station to end station.
Furthermore, amygdala, brainstem, pituitary gland and thalamus are most often associated with the processing of stimuli, because these structures receive, filter and encode the stimuli in terms of importance. But also the cerebral cortex of the frontal lobe and neurotransmitters plays a role in damping stimuli in healthy brains.



3. What is the nuisance caused by overstimulation?
What we found in the results of our survey (2016):

The nuisance of overstimulation varies from slight annoyance* to headache* and pain in the eyes*, ears* and skin*, nausea*, vomiting*, exhaustion* up to and including temporary paralysis* symptoms. In short: an overloaded system and a source of stress and being physically ill*.

Many people are forced to reduce their social contacts and become isolated*. Life in isolation is the only way to prevent overstimulation*.

Many brain injury victims are in a constant state of exhaustion due to chronic overstimulation*, which can hardly or not be trained* by rest and break strategies*.

[* source: our questionnaires, consider this as copyright]


Temporary worsening of, for example, paralysis of the affected side*, for example in the face, arm or leg and faltering speech is common*.
People have died due to chronic exhaustion caused by overstimulation*. Overstimulation should not be underestimated!

Several complaints have been discovered by us, our results are available for scientific research.

With continuous stress as permanent overstimulation, the body continuously produces stress hormones, which can also change the nervous system. This can lead to complaints such as stomach problems, auto-immune system change, cardiovascular disease, muscle function change, disturbance of sleep and sleep problems, depression, burn-out or anxiety disorders.

[* source: our questionnaires, consider this as copyright]

4. Three categories of overstimulation. Our survey showed (2016):

  • The form in which the limit is immediately exceeded. For example caused by background noise. Result: immediate overstimulation*.
  • The form in which stimuli accumulate (like a traffic jam) and at a certain instant they can no longer be processed. Then there is overstimulation.
    For example: someone perseveres for ten minutes in a company but then it becomes too much. This person should prevent this from happening by leaving the company within those ten minutes*.
  • Delayed overstimulation by hyperfocus*. When people train themselves knowingly and willingly 'to be able to do something', the overstimulation can strike mercilessly. In this case, training has adverse effects*.

    [* source: our questionnaires, consider this as copyright]

5. How can we recognize overstimulation? Our survey showed (2016):

In our survey, people indicated that symptoms of overstimulation vary per person*, per situation* and per moment*. This sometimes makes it difficult to recognize overstimulation for both the environment and for the person involved*. Overstimulation fluctuates from day to day as and when overload has already been stacked* The overstimulation trigger differs*.

The following problems are mentioned in our survey:

- Extreme (sudden) fatigue with long recovery*
- Bad headache*
- A feeling that there is a very tight tie around the head*
- Pressure in the head*
- No longer able to participate in a conversation*
- Difficult to get words, word-catching problems that can pass if the overstimulation is over*

- Faltering speech that can pull away as the overstimulation is over*
- Reduced articulation*
- Difficulty and slowness in thinking*
- Reduced concentration*
- Reduced coordination of movements*
- Contact avoiding behavior because there is an 'overload' in the head*
- Looking away and not being able to take part in the conversation in order to protect themselves from the stimuli*
- Irritation, (seldom) aggressive behavior, being short, snarling*
- Become more emotional*
- Hyperactivity, increased activity, being busy*
- Crying, fatigue crying*
- Being scared*
- Increased heart rate, higher breathing or restrained breath*
- Shaking, stiffening of the muscles, chance of falling over*
- Blinking or closed eyes*
- Nausea or vomiting*
- Temporary loss of facial muscles*
- Numbness of the affected side / reduced motor skills
- Get into short unconsciousness*
- Totally exhausted feeling*
"It is a big chaos in my head, busy in head, behind my eyes. I am intensely tired. It seems as if my head can burst apart at any moment. I often get sick, my thinking falters and I just feel total loss.", one of the respondents stated.
It is important to keep in mind that overstimulation differs per person*. 

[* source: our questionnaires 2016, consider this as copyright]

6. Different forms of overstimulation as we found in our survey (2016):

  1. Cognitive overstimulation*
  2. Sensory overstimulation (sounds, image, light, smell, feeling / sense of touch, position sense)*
  3. Emotional overstimulation*


Cognitive overstimulation

is caused by:

  • Own thoughts*
  • Multitude of what is said or being asked for*
  • Multitude of information to be processed, for example duplicate tasks or multitasking. Often, people with brain injury cannot do two things at the same time. It is either the one or the other. For example listening and working on something at the same time does not go well*.
  • Often information processing is delayed in case of brain injury, as a result of which stimuli can accumulate*.

This can lead to a situation in which the seriousness of the overstimulation is underestimated by healthcare professionals who are insufficiently trained to be alert to this.


Sensory overstimulation

is caused by:


Overstimulation by sound due to the inability to filter out background noise occurs, making it difficult to have a conversation.

In our survey (2016) we heard about: sound intolerance to music*, high or low tones*, child voices*, high ladies voices*, cutlery sounds*, teaspoons stirring in a glass* and the like. Also irritation with rhythmic sounds*, such as tapping a pen* occurs.

Many complaints are reminiscent of or are similar to hyperacusis, in which sound is often perceived as being too loud, maddening or hurting the ears.

[* source: our questionnaires 2016, consider this as copyright]


Visual overstimulation occurs while seeing busy patterns* or colors*, a multitude of cozy things in the house*, a piece of text without blank lines*, seeing movements*. See also the page vision problems.

[* source: our questionnaires 2016, consider this as copyright]

  •  LIGHT

Overexcitation due to light occurs, for example, in light reflection*, in certain light bulbs (halogen / tl)*, backlighting* or changes in shadow*. Notorious are the car rides on a road with lots of trees and a low sun behind the trees*.

[* source: our questionnaires 2016, consider this as copyright]


Overexcitation of feeling occurs in people who suffer from movement*, touch*, vibrations*, bastones*, etc. Sometimes overstimulation is experienced as pain through touch*.

[* source: our questionnaires 2016, consider this as copyright]


We observe the position of our body throughout the day, how our body relates to the world around us. In every muscle, joint and connective tissue there are minuscule sensors (proprioceptors) that let us know how we stand, sit or lie. In people with brain injury this can be experienced as dizzy* or unsteady on the legs*. So you can become overstimulated by movement, position of your head, uncertain feeling about how you move in a space*.

[* source: our questionnaires 2016, consider this as copyright]


Excitement by odors can be caused by the enhanced smell of food smells, natural scents, body odors, perfumes and deodorants*.

[* source: our questionnaires 2016, consider this as copyright]


Nociception (feeling pain) and thermoception (feeling warmth and cold) are also senses that can over stimulate. Those who have a lot of headaches are more likely to be overburdened and therefore over-stimulated.


Emotional overstimulation

In itself, it is questionable whether emotional overstimulation is part of cognitive overstimulation.

Emotional overstimulation has to do with the increased emotional vulnerability after brain injury*. Once overstimulated, the person can often no longer regulate the emotions*. The reactions are often more emotional and that can vary from person to person from fatigue-crying* to 'being more concerned with someone else*', frustration (also to oneself), being angry or aggression.

In emotional situations in someone's life, the 'measuring cup' appears to be full quickly and sensory stimuli are less well tolerated.


Crying often gives relief. For people with overstimulation, it does not necessarily have anything to do with sadness*. It should not be confused with compulsive crying or with emotional lability.


Overstimulation can not always be prevented. Some people experience emotional overstimulation in which their own thoughts are experienced more overwhelming than they are. The same applies to empathising and sympathizing with another.


Overstimulation functions in three directions. Body,  thoughts and emotions are harder to control if too many stimuli have come in*. Stimuli pile up*. If someone is already overstimulated, the cognitive "inbox" is filled up more quickly*.

[* source: our questionnaires 2016, consider this as copyright]

7. Congestion of stimuli

If more stimuli are received than the brain can handle, there are still a lot of (unprocessed) stimuli in the traffic jam. Your nervous system is busy working with the processing of all incoming 'info' of sound, image, smell, movement, feeling, thoughts or listening to everything that is said and the like.

Compare it with just as much traffic on a normal four-lane highway that suddenly has to use a country road ... including honking and light signals from the motorists who do not want to stand still!

[* source: our questionnaires, consider this as copyright]

8. Medical background of overstimulation

Overstimulation can be caused by

  • Broken filtering

All stimuli come in with the same power, that is, both the important and the unimportant stimuli. They are not filtered. The stimuli arrive unrestrained in the brain. The brainstem, the thalamus and the cerebral cortex (frontal) and the neurotransmitters should inhibit. Also specific damage in an area can cause the filter to be gone.


  • Diversion = delay

In case a brain injury causes the stimulation of brain cells to be guided around the injury, there is a delay in perception. This is not only when there is a focal, local injury, but also in the case of diffuse injury, spread over the brain. It takes longer before stimuli are interpreted. That is one of the causes that make a person with brain damage being overwhelmed by stimuli. This is also called delayed information processing.

There are more stimuli on hold than can be processed. Just like a PC that crashes in case the processor is too slow.


  • Fragmented observation

Many people with overstimulation due to brain injury observe every separate detail through hyperselection. For these people it is difficult to see connections between details and to see / view / listen to the whole.

This can be the case both on the auditory and on the visual level. As long as one sound stimulus is offered, the conversation is central and there is no music playing in the background, there is no problem with noise. But if there is a buzz in the background or more violent background noise, then the processing of the stimuli goes wrong.

It can also happen in the visual area. People can not ignore details, every drop on the windshield of the car when it rains and the windshield wiper, or every individual in a group, or every stone on a cobblestone road.


  • Distorted processing can cause overstimulation
    • Cerebral visual disorders CVI - double vision, varying sharp vision, depths can become immense or not, spaces can be observed more or less
    • Agnosia - not knowing the exact meaning of an object, sound, smell, etc.
    • Non synchronous processing of stimuli in the brain. Signals do not arrive synchronously at the brain area.


Perception we perform with


The senses

  • Eyesight - seeing
  • Hearing
  • Sense of touch - feel
  • Sense of smell - smell
  • Sense of taste - taste
  • Nociception - feel pain
  • Thermoception - feeling heat or cold
  • Sense of balance - balance
  • Proprioception - movements - body posture awareness



  • Perceive (basic cognition)
  • Attention and concentration (basic cognition)
  • Thinking (basic cognition)
  • Remember (basic cognition)
  • Applying knowledge (basic cognition)
  • Understand (basic cognition)
  • Language (basic cognition)
  • Assess (metacognition)
  • Reasoning ability (metacognition)
  • Sense of reality (metacognition)
  • Emotion (social cognition)
  • Empathy (social cognition)
  • Practical language skills (social cognition)

9. Summary of consequences of overstimulation as our survey showed in 2016*


  • No longer being able to think*
  • Fight-flight or stiffen reaction*
  • Extreme fatigue*
  • Vicious cycle of fatigue to prolonged exhaustion*
  • People have died from exhaustion due to long-term accumulation of overstimulation*
  • Physical complaints due to high stress hormone by prolonged stress due to overstimulation*, chance of nervous system change, autoimmune disorders, cardiovascular disease, muscle function change, disturbance of sleep and sleep problems, depression, burn-out or anxiety disorders.

    [* source: our questionnaires, consider this as copyright]

10. Project flooding

We established Project flooding as a patient interest organization. We hope to achieve that society, physicians and media take this target group seriously and to form a network that we can use to develop products but also for scientific research.

We encourage scientific research into overstimulation.
We are a recognized patient interest organization for overstimulation in brain injury since 2016.


11. Videos on overstimulation

We created a special page with videos on different types of overstimulation.

12.Download cards with concise explanation on overstimulation

You can download one of the documents below, print it and make sure to have it with you.


Card explaining overstimulation
PDF – 114,6 KB 1323 downloads
4 creditcards explaining overstimulation
PDF – 118,4 KB 1177 downloads

13. Stimuli-poor home decoration

Tip! Take a look, together with someone with brain injury, how you can make his or her home less overstimulating, so that it can become a quiet place to live. (in terms of image, patterns, light, used lamps, colors, sounds, smells, etc.)

- no TV, at least not in a central space
- quiet colors and preferably no patterns
- no lamels
- curtains or transparent roller blinds
- headphones for music / TV lovers
- PVC floor instead of laminate
- curtains
- play mat for the children
- separate hobby room, place to retreat
- do not direct your favorite seat towards the street side
- no high-gloss lacquer
- no reflective surfaces