Feb 15th Thee results of a scientific research are published at:

o   https://www.soffos.eu

o   https://www.overprikkeling.com/onderzoek-overprikkeling

o   https://www.hersenletsel-uitleg.nl/onderzoek-overprikkeling

A translation will follow soon. 

You can already translate the text of the PDF into your language with Google Lens.

English translation of this website


Sensory overload / Hypersensitivity / Over-stimulation / Flooding/Sensory processing disorder as a result of brain injury/ sensory overstimulation
On this site we explain the chronic, disabling and debilitating but invisible effects of sensory overload (flooding) in brain injury.

The Dutch website Hersenletsel-uitleg is the knowledge center of all possible information about causes, consequences, clinical pictures of brain injury.

The website is intended for people with brain injuries, caregivers, professionals and interested people. Project Flooding (started in 2013) is part of 'Hersenletsel-uitleg'. Our Dutch website is partly translated into English: Brain injury explanation.

Follow the news about scientific research and the interim report thereof, on the page https://www.overprikkeling.com/onderzoek-overprikkeling The final report is expected to be published in early December 2020.




Patient interest organisation

Since the very beginning in 2013, we have been working hard to make the issue of sensory overload (flooding/ sensory over-stimulation), as a consequence of brain injury, known. To come up with solutions and to initiate scientific research and recognition for a large group of people who can no longer participate in public life or family and family life; a forgotten group, a silent catastrophe. As a recognized patient interest organization for people with sensory overload in brain injury, in 2015 we became a foundation and gained the status of charity organization

In 2015 we became a member of the Dutch Brain Council. We represent the interests of people with overstimulation after a brain injury and after Whiplash Associated Disorders (WAD) in society and in politics and we work together with fellow patient interest groups and universities that are interested in scientific research into these invisible effects of brain injury. We do not require membership fees. We are not an association, you are a member with us if you are in one of our Facebook groups.

What is Sensory overload?

Sensory overstimulation is a debilitating situation that has a neurological origin that occurs when more information (in the form of stimuli) is received in the brain than it is capable of processing. The brain cannot properly filter environmental stimuli or does not allow them to pass sufficiently quickly. A stimulus is information that we get through our senses; to see, hear, smell, taste, feel (external stimuli) or through our thoughts or our body (internal stimuli).

Also, proprioception or position sensation / attitude can be overstimulated *. Proprioception is the ability to perceive the position of our own body and body parts. It seems that this information from various sensory cells or balance can also over-stimulate the brain. People just indicate that they feel seasick or 'drunk', as if the balance is disturbed.
Also thermoception (heat and cold) nociception (pain) can get overstimulated*.

There are various names for the problem of sensory overstimulation.

Overloading of neural networks, flooding of the senses or sensory overload are some of them. Every single name points out a serious and underestimated problem. It is a chronic and invisible result of brain damage. Not comparable to hyperacusis. Although it does happen that hyperacusis occurs at the same time as sensory overload. Sometimes there are multiple forms of sensory overstimulation happening at the same time.


Sensory overstimulation as well as a a consequence, also actually a condition in itself. In the case of brain damage, something has been permanently damaged in the brain. If, two years after the brain injury, the symptoms of sensory overload have not diminished, the unfortunate prognosis is that one should learn to live with it ... [* source: our questionnaires; consider this as copyright]

1. Introduction
What we found in the results of our survey:
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 full own body and or its partsour 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 of which is it often a difficult, and slow process to recover from*. Read more about brain fatigue or neurofatigue. [* source: our questionnaires; consider this as copyright]

2. Where in the brains?

The healthy brain inhibits the millions of stimuli it receives from the senses and from its own thoughts.
Brain structures such as the brainstem, thalamus (with various nuclei for specific stimuli), thalamic reticular nucleus (TRN), basal ganglia, pituitary gland, amygdala and cerebral cortex, especially the (prefrontal cortex) of the frontal lobe, play a role in attenuating stimuli in healthy brains.


Stimuli transfer involves the large brain cells (neurons) and intermediate cells (interneurons) and neurotransmitters: glycine, glutamate and GABA + serotonin must all cooperate undamaged in filtering. GABA to inhibit and glutamate and others to pass on stimuli.
In a damaged brain there are millions of other factors that play a role*. All text is subject to copyright policy!©

3. What are the complaints that are caused by over-stimulation? What are the symptoms caused by caused by sensory overload /overstimulation?

What we found in the results of our survey (2016):

  • Sensory overload/ overstimulation complaints vary from mild irritation to headache * 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 * can mean physical illness *.


  • Many people have to reduce their social contacts and become isolated *. Life in isolation is the only way to prevent over-stimulation *.


  • Many patients with brain injury are in constant depletion mode due to chronic over-stimulation *, which can hardly or not be trained * Learning  rest and pause strategies can help to understand and have a measure of control over this, but does not offer a cure*.


  • Temporary exacerbation of, for example, paralysis of the affected side *, for example, in the face *, arm * or leg * and failing speech * is common.


  • People have died due to chronic fatigue caused by overstimulation *. Overstimulation should not be underestimated!


NOTE! Several complaints have been discovered by us, our results are available for scientific research. [* source: our questionnaires consider this as copyright]

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.

4. Three categories of overstimulation

What we found in the results of our survey (2016):

  • The form in which the limit is immediately exceeded. For example background noise can result in 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 of people but then it becomes too much. This person should prevent this from happening by leaving the company of people within those ten minutes before they reach their limit.
  • Delayed overstimulation by hyper focus *. When people train or force themselves knowingly and willingly 'to be able to do something', the overstimulation can strike after completion of the task, and strike mercilessly. In this case, training has adverse effects*.

[* source: our questionnaires consider this as copyright]

    1. How can we recognize overstimulation?

    What we found in the results of our survey (2016):


    In our survey, people indicated that symptoms of overstimulation vary per person*, per situation* and per moment*. This sometimes makes it difficult to recognise overstimulation for both the environment and for the person involved*. Overstimulation fluctuates from day to day, for example, if the overload is already in place, it gets worse. * and the trigger for overstimulation differs *.

    The following problems are mentioned in our survey:

    - Extreme (sudden) fatigue that requires a long recovery*
    - Headache*
    - A feeling as if there is a tight band around the head*
    - Pressure in the head*

    - No longer able to participate in a conversation*
    - Word finding problems, these pass once the overstimulation is over* Difficulty gettingt he words in your head out of your mouth, or word-catching problems (hearing something different, or incoherently) this too passes if the overstimulation is over

    - Faltering speech that passes once the overstimulation is over* Aphasia*  Speech apraxia*
    - Reduced articulation*
    - Difficulty and slowness in thinking*
    - Reduced concentration*
    - Reduced coordination of movements*

    - Contact avoiding behaviour 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, aggressive behaviour, being short tempered, irritable , having a short fuse*
    - Being 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*, Loss of muscle tone*
    - Half-sided paralysis*
    - Temporary loss of facial muscles*
    - Numbness of the affected side / reduced motor skills*
    - Blinking or closed eyes*

    - Epileptic seizures*

    - Nausea or vomiting*
    - Short absences of consciousness*
    - Totally exhausted feeling*


    "It’s very chaotic, or busy in my head, behind my eyes.  I am extremely tired. It seems as if my head can burst open at any moment. I often get sick, my thinking falters and I just feel totalled." one of the respondents stated.

    It is important to keep in mind that overstimulation differs per person.*

    [* source: our questionnaires consider this as copyright]


    1. Different forms of overstimulation

    What we found in the results of our survey(2016):

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


    Cognitive 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

      Sensory overstimulation is caused by:


      • NOISE

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

      In our survey 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.


      • VISION

      Visual overstimulation occurs while seeing busy patterns* or or colors (USA) colours (UK)*, a multitude of cozy things in the house*, a piece of text without enough spacing in between the lines*, seeing movements*. See also the page vision problems.


      •  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*.



      Overstimulation of tactile feeling occurs in people who suffer from extreme sensitivity to  movement*, touch*, vibrations*, bass tones*, etc. Sometimes this overstimulation is experienced as pain through touch*, physical pain.



      We observe the position of our body throughout the day and 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 multitude of information can be experienced as feeling dizzy* or unsteady on the legs*. One can become  overstimulated by things such as movement*and position of your head*, this leads to feelings of uncertainty about how to navigate your body*.


      • SMELL

      Excitement by odors can be caused by the enhanced smell of food smells, natural scents, body odours, perfumes , scent and deodorants, household and hardware chemical substances, cleaning materials, paint, glues, multiple and new smells such as food markets, visiting new cultures and places*. 




      Nociception (feeling pain) and thermoception (feeling warmth and cold) are also senses that can over stimulate. Those who have a lot of headaches for example are more likely to be overburdened with sensations  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 emotionally extreme 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 fill up 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 as overwhelming. The same applies to empathising and sympathizing with another.


      Overstimulation functions in three directions. Through our bodily sensations, tho through our thoughts and emotions which are harder to control if too many stimuli are perceived* and stimuli pile up*. If someone is already overstimulated, the cognitive "inbox" becomes full.*

      [* source: our questionnaires consider this as copyright]


      1. Congestion of stimuli

      If more stimuli are received than the brain can handle, , the stimuli begin to pile up, meaning that there are still a lot of (unprocessed) stimuli in the traffic jam.
      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!

      Your nervous system is constantly busy working with the processing of all incoming 'info' of sound, image, smell, movement, feeling, thoughts or listening to everything that is said all the other sensations that are a normal part of the lives we live. People with brain injury can have big problems with processing stimuli. They can become very ill by simply processing normal information.


      1. Medical background of overstimulation

      Overstimulation can be caused by

      • Broken filtering

      All stimuli enter the brain as equals, 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 process the information, judge it’s relevance and then inhibit the less important information. Specific damage in an area can disrupt the filter or destroy it completely.


      • Diversion = delay

      When a brain injury causes brain cell activity needed to process information to be re-routed 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 because the processor is too slow.


      • Fragmented observation

      Many people with overstimulation due to brain injury observe every separate detail through hyper selection. 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 obtrusive background noise, then the processing of the stimuli goes wrong.

      This can also happen in the visual area. People cannot ignore details, every drop on the windshield of the car when it rains and the action of 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 as larger or smaller than they actually are
        • Agnosia - not recognizing 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 / Visual System (sight)
      • Hearing / Auditory System (sound)
      • Sense of touch / Tactile/Somatosensory System (touch)
      • Sense of smell / Olfactory System (smell)
      • Sense of taste / Gustatory System (taste)
      • Interoceptive System (state of internal organs)
      • Nociception (feel pain)
      • Thermoception (feeling heat or cold)
      • Sense of balance / Vestibular System (balance)
      • Proprioception / Proprioceptive System (muscle/joint movement, where body is in space, movements)



      • 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)
      1. Summary of consequences of overstimulation *
        What we found in the results of our survey (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]


      1. Project flooding

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

      We encourage scientific research into overstimulation.
      We are a recognised patient interest organisation for overstimulation as a result of brain injury since 2016.

      In 2019, we received the Gold medal of honor for particularly good work for people with brain injuries.


            1. Videos on overstimulation

            We created a special page (see link) with videos on different types of overstimulation.

            Back to top


            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.


            English creditcard to explain one becomes ill from lights and sound
            PDF – 33,8 KB
            Card explaining overstimulation
            PDF – 114,6 KB
            4 creditcards explaining overstimulation
            PDF – 118,4 KB


            1. 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

            If you have to be somewhere, or do something that you know will cause you to become overloaded – schedule in breaks around this event or activity. If going to a family function you might find a quiet place to go to for breaks before you become overloaded.

            Take little mini breaks throughout your day, and life.

            Think in an ‘off peak’ kind of way. ‘Off Peak’ usually means quieter times – look for these in daily life.