Your day to day experience tells you that focus on practicing a new skill, doing a intensive project or homework, or performing another cognitively demanding task can affect breathing. Sometimes our breathing may be inhibited; in other cases we may notice it speed up – its rate increasing.
But there has been little systematic study of the effect of what is called mental load (or cognitive load) on breathing – until Grassmann and his colleagues at the Research Group on Health Psychology, University of Leuven, did a review on all the published studies on this process.
In this short blog-post we’ll see what they found – and how it can help us improve our cognitive performance and resilience.
What Is Mental Load?
Let’s define mental load. Mental load is a measure of mental task demands – such as speed or complexity. If a task exceeds our capacity to do it, mental load is high. Mental load is not the same as mental stress, since it is typically accompanied by neutral or even positive feelings of being challenged.
But a high mental load, for a long duration, can result in mental stress, poor performance and burnout – as most of us have experienced at some point.
One cause for this – and it’s not at all obvious – is what’s happening with our breathing.
The Breathing Study and What It Tells Us
“…mentally demanding episodes are clearly marked by faster breathing. …In addition, we found that cognitive load may lead to overbreathing as indicated by decreased CO2 but is also accompanied by elevated oxygen consumption and CO2 release.”
What Are The Effects Of Lower Blood CO2 On The Brain?
Reduced CO2 reduces the oxygen available because it constricts blood vessels and this impairs circulation. The carotid artery to the brain (the main blood vessel supply in blood to the brain) can constrict up to 50% through overbreathing – greatly reducing blood flow to the brain.
In more technical terms:
We need blood CO2 to be 40 mm Hg pressure in the lungs and arterial blood. Every 1 millimeter drop of CO2 reduces blood flow to the brain by 2%. It takes between 2 and 9 minutes to significantly reduce CO2 in the blood.
Free radicals – result of the breakdown of oxygen. We have anti-oxidants (e.g. Beta–carotene, Vitamin C & E) to deal with these. Overbreathing results in an accumulation of free-radicals which results in oxidative stress, which destroys cells and is implicated in aging and a number of diseases including cancer.
And it gets worse.
The reduced blood flow to his brain not only reduces oxygen supply. it also increases neuronal excitability resulting in stress and tension and reduced cognitive performance.
Free radicals result from the breakdown of oxygen. We have anti-oxidants (e.g. Beta–carotene, Vitamin C & E) to deal with these – our anti-oxidants ‘balance out’ the free radicals.. But Over-breathing upsets this balance and results in an accumulation of free-radicals. This causes oxidative stress that destroys cells, and is implicated in aging and degenerative diseases, including arthritis, diabetes, heart disease, cancer and Alzheimer’s.
Your blood is made up of acids and alkaline bases. The amount of acids and bases in your blood can be measured on a pH scale – the lower the pH the more acidic. It’s important to maintain the correct balance between acids and bases. Even a slight change can cause health problems. Normally, your blood should have a slightly higher level of bases than acids. CO2 is an acid and low CO2 due to respiration results in increased blood pH (more alkaline) and respiratory alkalosis. Symptoms of this include light-headedness, nausea and confusion.
Recap
Look at the man in the photo above. He’s overbreathing in a high cognitive load task. 10 minutes into his work – and his brain is already being beginning to be starved of oxygen due to reduced CO2 and constricted blood vessels.
An hour or two into his work and his CO2 levels are very low. He’s feeling tense and a little confused. He’s got a build up of free-radicals which are damaging his body. He’s upset his critical pH balance, and the low acidity of his blood contributes to his craving acidic foods such as chocolate, coke and chocolate!
How To Change Your Breathing For Better Health, Mental Resilience & Performance
To stop over-breathing, you need to breathe calm and quiet and relaxed – through your nose, not mouth, and using your diaphragm, not just your chest. This helps the CO2 to slowly accumulate in the blood, which allows the blood vessels to open to increase oxygen supply.
To change your breathing you need to bring your attention to your breathing – become mindful of your breathing. It’s a type of meditation.
Start by placing one hand on your chest and your other hand just above your navel, to become more aware of how your body behaves when you’re breathing.
Then gently slow down your breathing, diminishing the size of each breath as you go along – with the in-breath a little shorter than the out-breath. All gentle and relaxed. You can do this to the point that you feel a tolerable need for air – a kind of air hunger. This means that there’s a slight accumulation of carbon dioxide in your blood [which sends a signal to your brain saying ‘breathe’]. Now, when you have an air hunger for about three or four minutes, you will start experiencing the effects of an accumulation of CO2. Symptoms of this may include:
- Body temperature increasing. You may feel that your hands and face are warmer.
- You may have increased saliva in your mouth – a sign that your parasympathetic nervous system has been activated, helping you relax.
Perhaps try this kind of breathing every half an hour or so, as you take breaks from the work you are doing.
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