The balance system
The balance system works by coordinating information in your brain from the three senses used for balance: your balance organ in your inner ear, your eyes and your internal sense of position/movement in your body.
If you feel dizzy, it means that your brain has not been able to coordinate the information from all the balance senses properly. This could be due to a problem in the brain or with any of the balance senses.
In vestibular disorders (e.g. Ménière’s), the balance organ in the inner ear is affected. As the balance organ is faulty, the brain becomes more dependent on information coming from the eyes and sensors in your body. This makes you much more sensitive to situations which can cause dizziness, such as disorientating environments and times when you are under stress. Therefore, not all the symptoms of dizziness experienced will be due to the balance organ, some will be caused because your balance system cannot cope with the situation you are in.
What processes in the brain can affect balance?
Conflicting information from the balance senses
An example of this is when you are sitting on a train and the train next to you starts to move, creating the feeling that you are moving. This conflict of information results in dizziness, even in people who do not have problems with their balance senses. Motion sickness is another example of conflicting information from the balance senses.
Emotions and thoughts
When you feel particularly stressed, anxious, angry or fearful, you may be more likely to experience dizziness. This is because some of your body’s automatic reflexes are linked to your emotions and thoughts through a process called the fight or flight response. Your body interprets any strong emotions or frightening thoughts as a signal that you are in danger and automatically prepares your body to either fight or run away. Your heart rate increases, your breathing gets faster and blood is pumped round your body quicker. A side effect of this is that you may feel sick or dizzy as breathing too fast causes you to take in too much oxygen.
Your emotions can also be directly influenced by your thoughts. If you think that dizziness will lead to further problems this can make you feel more stressed or anxious when you become dizzy.
Tiredness and concentration
When you are tired or doing things you have to think about this can affect your balance. If you are concentrating on a mental task, your brain has less capacity spare for other tasks – such as maintaining your balance. It takes mental effort and capacity for your brain to cope with conflicting information about balance and so you may become tired and unable to concentrate when you are dizzy and while your brain is adjusting after a vertigo attack.
Medication and alcohol
Some medications list dizziness as a side effect. If you take more than four different types of medication this may also cause dizziness and increase your risk of falling. Alcohol can also cause dizziness. It suppresses certain processes within the brain including those responsible for balance.
Other medical conditions
Dizziness and imbalance can also be the result of damage to areas of the brain that coordinate balance and are often the cause of dizziness in people who have multiple sclerosis, stroke or Parkinsons disease.
How does vision affect the balance system?
In Ménière’s and other inner ear balance disorders, your brain must rely more on your sense of vision to balance more than people who do not have a balance disorder. As a result of this, your balance system can be more sensitive to confusing or disorienting information about your balance coming from your eyes. Dizziness can therefore be triggered by complex or moving visual environments (sometimes called visual vertigo), such as busy roads, moving crowds, or walking down the aisle of a supermarket where the shelves provide repetitive complex visual patterns. Other disorienting environments include travelling in a car or going up or down in a lift or an escalator.
Visual environments which can affect balance include:
Not enough visual information – e.g. darkness, open spaces, travelling in a lift
Your eyes get their information about which way up you are from the environment. This information is taken from vertical structures, such as buildings, trees and lamp-posts. These vertical structures need to be quite close to you to be useful for your balance system. Several types of environments do not provide enough visual information for your brain and so can result in dizziness and unsteadiness. The most obvious of these is at night when it is dark, or when you are somewhere that only has dim lighting. There is also not enough visual information nearby when you are in large flat and open spaces (e.g. a field or park), or looking down from heights. Inaccurate visual information can also result in dizziness and unsteadiness. When you are travelling in a lift or on a boat without a view, you do not have accurate visual information about how you are moving, because your visual environment is moving with you. The balance organ in your inner ear can tell you are moving and sends conflicting information to your brain.
Too much visual information – e.g. motion, patterns, flickering lights
The balance system can also become overloaded when you take in more visual information than you are used to dealing with. This visual information conflicts with information coming from your other balance senses resulting in dizziness and unsteadiness, such as:
- Motion - standing next to a busy road, watching a car chase on TV or being in a crowded place. This is because the continuous movement across your line of sight keeps sending new signals to your brain about your visual environment. These signals are an unreliable source of information for your balance system and it can become confused as to whether it is you or your environment that is moving. Slow moving environments like escalators, looking at clouds or a scrolling computer screen can also trigger dizziness and unsteadiness.
- Complex Patterns - environments where there are repetitive or complex patterns can also overload the balance system with too much visual information. The most common environment like this is a supermarket with long narrow aisles that are stacked high with many shapes and colours. Other environments include patterned floors/carpets, or looking at stripy surfaces (e.g. wallpaper).
- Flickering lights - just as darkness or dim lighting prevents your eyes from getting enough information, lighting that flickers also means that your eyes are not getting reliable information about your visual environment. Environments that involve flickering lighting include travelling in a car when the sun is shining through the trees or at night when the oncoming car headlights are flickering, and shops or other places that use fluorescent lighting. Programmes on TV and older computer screens can also flicker. Because your brain has a limited capacity for what it can attend to at any one time, attending to a change in lighting means that your brain has less capacity to co-ordinate your balance.
How does the rest of my body affect my balance?
Sensors in your skin, muscles and joints around your body send signals to the balance system about where all the parts of your body are, if they are moving, and whether they are touching anything. Your balance will be better when you are sitting than when you are standing, and standing on two feet will give you a better balance than when you are standing on one foot, as more parts of your body will be sending signals to your balance system. Your balance is also affected by the type of surface you are walking on, such as escalators, stony paths, an icy hill, narrow beam or sand.
When fewer signals are being sent from your body, your balance system is more reliant on the signals from your eyes and balance organ. An example of this is riding a bicycle. The signals from your body are dramatically reduced because you are not in direct contact with the ground, the bicycle and the pedals move, and you are reliant on a narrow surface (two thin wheels one in front of the other). Regular exercise is important for maintaining flexibility and strength, which can help you to balance. The stronger and more flexible your muscles and joints are, the better your body will be able to deal with different surfaces.
Text taken from The Balance System by Professor L Yardley and Dr S Kirby, School of Psychology, University of Southampton. Download the full text as a PDF.