Sensory Overload, or Hypersensitivity, can be something that can be experienced after significant brain injury some people find that exposure to normal, everyday levels of things like bright lights, loud noises or touch is now uncomfortable, overwhelming or distressing.

This problem may be referred to as ‘hypersensitivity’, ‘over stimulation’ or ‘sensory overload’ and can lead to fear, anxiety and avoidance of that stimulus.

For example, keeping curtains drawn to avoid light and avoiding noisy situations such as supermarkets.

A ‘stimulus’ is something that requires or causes a response. A stimulus may have its origin in ‘external’ events (e.g. a noise, bright light) or ‘internal’ (e.g. a thought, preoccupations, pain, discomfort, feelings).

It is more common for people to experience loss of sensory function rather than ‘hypersensitivity’ following a significant brain injury. Examples of sensory loss include:

• Loss of sense of smell/taste due to neurological injury.
• Hearing impairment due to fracture of the temporal bone and damage to the vestibulocochlear nerve.
• Changes to sense of touch.

Common problems experienced after significant brain injury include cognitive impairments of processing and attention.

This may result in the person experiencing overload in relation to one or more senses.

Due to changes in attentional ability, screening out intrusive background stimuli may be more difficult eg. dripping tap, another person’s conversation, sunlight.

This means that background stimuli can often monopolise the person’s attention, potentially leading to the person becoming distracted in the context of trying to complete a task.

This may result in failure to complete the task which may be associated with frustration and potentially anger. In the context of changes in attentional ability, it is helpful to try and limit intrusive background stimuli (e.g. dripping tap) in order to maximise the person’s attentional ability.

In the context of cognitive changes described above, the person may become preoccupied with trying to block out/ignore intrusive stimuli.

This can result in the development of unhelpful avoidance behaviours (arising from attempts to block out as much of the intrusive stimuli as possible).

This could potentially lead to a situation in which the person is going to extreme lengths to avoid certain types of sensory stimuli (e.g. habitually wearing earplugs to reduce the impact of noise or wearing sunglasses to decrease the impact of light).

Similarly, if someone experiences headaches associated with sensitivity to sound or light, then this can also lead to avoidance behaviours.

Avoidance behaviours may lead to ‘hypersensitisation’ of, for example, auditory and visual sensory systems, resulting in even modest intensity stimuli being experienced as uncomfortable (i.e. feelings of overwhelm/sensory overload/hypersensitivity to the problematic stimuli).

As exposure to more intense stimuli is experienced as uncomfortable, this can be compounded by thoughts that sensory experiences are harmful, for example exposure to sound will further damage hearing or exposure to bright light is harmful.

A cycle of over protection with progressively worsening symptoms may emerge, the whole process potentially being magnified by associated anxiety.

It is important to be aware that sensitivity to light and noise are very common symptoms after a mild traumatic brain injury.

These symptoms are more common after a mild traumatic brain injury than they are after a more severe one.

They are also common following head injuries in which there has been no loss of consciousness and no period of post traumatic amnesia (meaning that actual injury to the brain itself did not occur).

For further information about mild brain injury, please see: Head Injury Symptoms.