Breathing is considered by most cultures as the key to life, since life starts by our first breath (although that is debatable) and ends with our last breath.
We breathe on average 20.000 times per day – how often do we pay attention to it; despite the impact our breath has on our minds?
Our breath is a tool we always have at our disposal to focus our minds, manage our emotions and stress, or increase our level of energy or our creativity. You probably noticed that simply taking a deep breath is a very effective way to calm down your mind.
Most meditation practices start with paying attention to our breath, without modifying it. Simply paying attention to the breath leads to activation of the prefrontal cortex, the thinking part of the brain, which inhibits the emotional centers of the brain. This alone can be very effective in calming the mind, but we can also decide to modify our breath with specific breathing exercises to further leverage this tool.
Breathing techniques helping to get back in control of our minds have been around for millenniums, and neuroscience is revealing the basis of their efficiency.
The way we breathe affects our mind on 3 different levels: gas exchange (O2 and CO2), peripheral nervous system, central nervous system. This article will explore the scientific basis of a few breathing practices, and how they can be used to control our minds.
Our breath rhythm affects brain oxygenation, but not the way we imagine
Breath is fascinating because it is automatic, but we can also modify it voluntarily, unlike most other biological rhythms such as our heart rate. We can decide to accelerate it, deepen it, or slow it down and even hold our breath. When we take a deep breath, we exchange 10 times more air than in a normal breath (around 500ml), which shows that the lungs can stretch deeply, and we do not exploit that possibility naturally unless we do an effort that requires it.
The main function of breathing, as we learned at school, is to bring some O2 in the blood, and eliminate CO2. However, blood O2 levels do not vary that much with our breathing rhythms thanks to hemoglobin, which captures O2, and buffers its concentration. This allows our organs too still receive O2, even if we hold our breath for a little while. Unlike O2, CO2 levels vary with the way we breathe, and CO2 acts as a regulator of our breath and brain oxygenation.
We might think that breathing faster and deeper will lead to more blood oxygenation, and in turn to more tissue and organs oxygenation. In reality, the opposite is happening, at least for the brain. Counterintuitively, 1 minute of hyperventilation leads to a 40% drop in brain oxygen levels. The opposite is also true: slow breathing or breath holding leads to higher brain oxygenation. How Is this possible?
When we hold our breath or breathe very slowly, CO2 accumulates in the bloodstream, and this has 3 effects leading to higher brain oxygenation:
- Bronchioles in the lungs dilate, leading to increased O2 uptake into the bloodstream
- Blood capillaries irrigating the brain dilate (vasodilatation), leading to more blood in the brain
- CO2 accumulation leads to a drop in blood pH, which weakens the strength of the link between hemoglobin and oxygen. In other words, oxygen is released from the bloodstream into the brain tissues. This is called the Bohr effect.
The biological role of these mechanisms is to protect our brain from hypoxia when we lack fresh air, but the trigger is blood CO2 levels and not low O2 levels. Of course, if the retention is too long, oxygen will start becoming scarce, which will have other consequences. With the right training, some apneists can hold their breath for over 10 minutes. Without going to those extremes, in some yogic breathing exercises, we hold our breaths for periods of 1 min to 1 min 30 s. Such relatively short retentions have a beneficial effect on our brain oxygenation, and they also lead to a relaxation of the nervous system.
Since the prefrontal cortex, the CEO of the brain responsible for higher cognitive functions, uses the most energy (it represents 4% of the brain volume, but uses 80% of its energy), it is the first one to be affected by brain oxygen levels. When we hold our breath for a reasonable time, we oxygenate our prefrontal cortex, and we can perform higher cognitive functions. When we hyperventilate, the prefrontal cortex lacks oxygen, which has 2 consequences:
- First, it is much more difficult to perform higher cognitive functions. Decision-making, information processing, thinking, problem-solving, task completion, memory, and communication effectiveness are all altered.
- Second, our brain’s CEO stops performing its inhibitory function over emotional centers of the brain, located in the limbic system. This leads to the release of emotions that are otherwise held under control, or the intensification of emotional states, since the Prefrontal cortex cannot play its emotions gate-keeper role anymore. This is used by some therapeutic approaches to make refrained negative emotions emerge through hyperventilation in order to deal with them.
Most ancient breathing practices developed by Yogis involve breath holding, which has the opposite effects: relax the mind, empower our thinking brain, and keep under control our emotional brain.
In summary, our breathing rhythm and intensity affect both our cognitive functions and our emotional states, and CO2 is a key regulator of those processes.The slower we breath, the more we calm down our minds and emotions and can think clearly thanks to brain oxygenation.The faster we breath, the more our judgment and reasoning are altered, and negative emotions can also arise.
Our breath affects the peripheral nervous system
The peripheral nervous system allows the brain to communicate with the organs, and it is composed of 2 branches: the sympathetic nervous system, which is activated in case of a threat or in case of stress and is responsible for the fight or flight response, and the parasympathetic nervous system, which has the opposite effect: calming down the whole system and preparing for human connection.
Both branches are permanently in balance, and our breath can affect this balance. This starts with receptors in the lungs and bronchia that detect the stretch of the lungs. When they detect lungs stretching, which means that our breath is deep, they activate the parasympathetic system. Activation of the parasympathetic nervous system relaxes the breathing rhythm, the heart rhythm and blood pressure, muscle tension, but it also sends information upwards towards the brain in order to calm the mind.
Therefore, when we take slow deep breaths or when we hold our breath, this mechanism contributes to relaxing the mind.
Our breath affects the central nervous system through nasal breathing
A team of researchers from Chicago University leveraged the fact that patients suffering from severe epilepsy already had electrodes implanted in various parts of the brain to study the link between breathing and brainwaves in various regions of the brain. What they found is that the rate of nasal breathing is acting as a master clock for brainwaves in different parts of the brain. Nasal breathing is first entraining slow delta waves in the piriform cortex responsible for the sense of smell, and these waves entrain faster beta waves in the medio-temporal lobe (still in the cortex). Those waves in turn entrain beta waves in limbic areas, and in particular in 2 very interesting parts: the amygdala, which is responsible for emotions processing, and the hippocampus, with is responsible for memory formation and retrieval. This process did not work when patients breathed through the mouth, which indicates that it is really driven by the smell receptors in our nasal mucosa. From these observations, they inferred that nasal breathing influences both our memory and our emotions. In order to test that hypothesis, they tested healthy people on their memorization skills and their emotional discrimination skills by asking them to recognize emotions in pictures of faces. They compared the results when showing objects or pictures during the inhalation phase and during exhalation phase. The results were quite clear: we are better at memorizing things and recognizing emotions when we inhale than when we exhale.
These findings tend to validate 2 instructions that most Yoga teachers give to their students:
- Breathe through the nose. Otherwise that regulatory mechanism does not occur if we breathe through the mouth.
- Lengthen the exhale compared with the inhale. Many breathing practices involve exhaling two times longer than we inhale. This reduces the activation of the amygdala and hippocampus. When we want to relax our mind and build mindfulness skills, we want to focus our attention on the present moment, and not be bothered by memories, even less if they are associated with strong emotions.
Breathing and brain polarity
Most people know that we have 2 brain hemispheres that function in different ways, but few know that their activation is connected with the breath.
The right hemisphere‘s way of thinking is big-picture oriented and non-verbal. It is better at seeing the overall context than the left hemisphere, at body sense and visuo-spatial perception. In terms of emotional processing, it is much more pessimistic than the left hemisphere. Its evolutionary function is to protect is owner from taking too risky decisions and avoiding danger.
The left hemisphere’s way of thinking is analytical and verbal. It is better than the right hemisphere for in-depth, linear problem solving and fact-based processed. It is also focused on wordily thoughts and linguistics. It is also more optimistic than the right hemisphere, and when it is dominant, it leads to relaxation, but also to a proactive state of mind.
Of course, no brain hemisphere is better than the other. They both have complimentary and balancing functions, and the ideal situation is to have both brain hemispheres active and balanced.
Unfortunately, this is not what happens most of the time, and this is linked to a particularity of our breathing that many people ignore.
We all have a nostril dominance cycle. At any given moment, we have one nostril which is dominant compared with the other. Sometimes it is not so clear and sometimes the difference is really obvious because one of our nostrils is completely blocked. In order to notice that, you can simply place a thumb 1cm in front of each nostril and notice if you feel a difference in airflow between the 2 sides, or you can also block one nostril after the other, and notice on which side it I easier to breathe.
The nostril dominance varies every 2 to 2,5h on average, although the duration of that cycle is highly variable, and also dependent on our emotional state.
What is even more interesting is that this cycle is directly linked with brain hemisphere dominance. When the right nostril is dominant, the left hemisphere is dominant and vice-versa.
The first takeaway is that we are going to be better at analytical problem solving when our right nostril is dominant, and better at big-picture thinking when our left nostril is dominant.
Luckily for us, yogis know for thousands of years how to modify this cycle. They have developed a breathing technique called alternate nostril breathing (anuloma viloma or nadi shodhana in Sanskrit) that balances the activity of the 2 brain hemispheres. It has been proven to balance the alpha and beta brainwaves between both hemispheres, leading to a more balanced control of emotions.
This technique is also highly effective at decreasing heart rate and blood pressure, and increasing the parasympathetic activity, which leads to greater relaxation.
Given the complimentary ways of thinking of our 2 brain hemispheres, the best way to favor creative thinking is to have both hemispheres working together when we analyze a problem, in order to tackle it through different angles, both analytical-driven and big-picture oriented. This is what this technique has to offer on top of bringing relaxation and emotional control.
We hope the scientific insights inspired you to pay more attention to the way you breath. If you would like to know more and practice for 5 days with a stunning mountains view, join our annual Executive NeuroMindfulness Retreat, Spain.
Key messages:
- We have seen in this chapter that breathing is a very powerful Mindfulness tool.
- The simplest use of breathing is to place our attention on breath, which is the gateway to meditation, and will lead to a more relaxed and focused mind. Then, by learning to slow down and deepen our breath, we can further relax our mind and nervous system.
- Exhaling over a longer time than the exhale relaxes the nervous system and the mind through the activation of the vagus nerve.
- Breath retentions are also an interesting tool, since they lead to more brain oxygenation, in particular in the Prefrontal Cortex, the brain’s CEO.
- Finally, we can also act on our nostril dominance cycle to balance our 2 brain hemispheres through alternate nostril breathing. This will not only calm down our minds and relax our nervous system, but it will also help us with creative thinking, since we will be able to address issues through both angles, analytical and big picture.
Sources :
Kamath A. et al., 2017. “Effect of Alternate Nostril Breathing Exercise on Experimentally Induced Anxiety in Healthy Volunteers Using the Simulated Public Speaking Model: A Randomized Controlled Pilot Study.” Biomed Res Int. 2017
Zelano et al., 2016 . « Nasal respiration entrains human limbic oscillations and modulates cognitive function » J. Neuroscience, 2016
Kahana-Zweig et al. , 2016. “Measuring and characterizing the human nasal cycle”, PLoS One. 2016
David Hecht, 2013. ” The Neural Basis of Optimism and Pessimism”, Exp Neurobiol. 2013
Litchfield P., 1999. “A Brief Overview of the Chemistry of Respiration and the Breathing Heart Wave”. The newsletter of the BSC, 1999
Stancák A et al., 1994. “Changes during forced alternate nostril breathing”. Int J Psychophysiol. 1994
