Just Breathe.

We have been breathing without help since the day we were born and yet, everywhere we look we are told to focus on our ‘breathing’ in order to stay calm and reduce stress. Is there really any science behind this claim and does this really work? Exactly how many breaths per minute should we breathe for maximal effect?

Quick recap of the stress response

If you suddenly find yourself in a highly stressful situation, your brain triggers off a chain reaction that results in cortisol and adrenaline being released and in your becoming tense and anxious. The chain reaction is mediated by one half of your ‘automatic’ nerve network known as the ‘sympathetic’ nervous system. Normally, the sympathetic nervous system works in concert with your 'parasympathetic' nervous system to modulate various parts of your physiology. For instance, your heart is always receiving both sympathetic and parasympathetic input. If it is beating too fast, the volume or 'tone' of your sympathetic input is reduced and the tone of your parasympathetic input is increased. During an acute stress response, your sympathetic tone rapidly increases and your parasympathetic tone falls. The moment your stressful experience is over and you are relaxed again, your sympathetic tone falls and your parasympathetic tone rises. In chronic stress, your sympathetic tone stays raised, even when you are resting.

The stress signal and your breathing pattern are linked (this gets technical, so feel free to skip to the next paragraph!)

Whenever we breathe in, a nerve called the phrenic nerve makes the flat sheet of muscle at the bottom of our lungs (the diaphragm) contract, which sucks air into our lungs. The phrenic nerve is turned on and off by a signal generator. Nerves that control the process of breathing line a part of the brain’s medulla called the ‘ventral respiratory column’. Within this column lies a specific nerve circuit known as a respiratory ‘central pattern generator’. We also find nerves mediating the action of the sympathetic nerves (in the rostral ventrolateral medulla) in this exact same region. We think that such close proximity of breathing signal generators and the nerves mediating sympathetic activity may explain why one can so closely influence the other. Breathing changes sympathetic tone and changes in sympathetic tone changes how we breathe. The two are tightly linked.

Are there any studies?

Although there are not many studies on the effect of changing the pattern of breathing on sympathetic tone, the studies that do exist suggest that we might be able to control our breathing to bring down sympathetic tone, at least in some cases.

Slow and steady breathing has been shown to suppress baseline sympathetic activity. As the lungs expand during inspiration, sympathetic tone goes down. Reducing the rate of breathing reduces sympathetic tone. In one experiment on patients with chronic heart failure who tend to have high sympathetic tone at rest, reducing the rate of breathing from 16 breaths per minute to about 7 breaths per minute and breathing in twice the usual volume of air resulted in a lowering of sympathetic activity (as detected in muscle), by a third.

A high blood pressure can be a sign of a high sympathetic tone. An abnormally high blood pressure may be lowered through controlled breathing. In one small study, taking slow, deep breaths for only 5 minutes at a rate of 6 breaths per minute brought high blood pressures down. In another study on patients with diabetes and a high blood pressure, guided breathing sessions for 12 minutes every day for two months was found to reduce sympathetic input to the heart (seen as a raised heart rate variability index) and reduce pulse pressure.

Feeling the Heat

This close relationship between breathing and sympathetic tone becomes particularly enhanced in certain situations. One such scenario is in the presence of heat. As your body temperature rises, breathing becomes even more effective at reducing your sympathetic tone.

Putting it into practice

Now we know that breathing is so closely coupled with sympathetic tone, how can we hack it to improve our stress levels?

1. A deep inhale where you expand your lungs as much as possible brings down your sympathetic tone.

2. If you are healthy, then slowing your breathing rate down, aiming for about 6-7 breaths per minute has been shown to reduce sympathetic activity.

3. Remember, the stress response is a chain reaction. The further down the chain you are when you intervene, the less likely you are to stop the reaction. The instant you first become aware that the situation you are in is about to become stressful, control your breathing. Slow it down and breathe deeply. Then, even if your emotional brain triggers a stress reaction, you will have a tight hold over your sympathetic system to minimize its activity.

4. Your stress response enhances your emotional brain, which suppresses your rational brain, so reducing your sympathetic tone through slow and deep breathing could hypothetically enhance your concentration and mental focus.

Having short bursts of slow, deep breathing scattered across the day may keep you going when you are highly stressed. You need your sympathetic tone to drop at night in order to be able to fall asleep and so controlling your breathing while you are counting those sheep may even help you drift off to sleep!

Happy Breathing!

N.B.

This site is for discussion only and should not be used as a source of medical information. Please consult your medical doctor before making any changes to your diet, lifestyle or medications.

References

Dick TE, Mims JR, Hsieh YH, Morris KF, Wehrwein EA. Increased

cardio-respiratory coupling evoked by slow deep breathing can persist in normal humans. Respir Physiol Neurobiol. 2014 Dec 1;204:99-111.

Harada D, Asanoi H, Takagawa J, Ishise H, Ueno H, Oda Y, Goso Y, Joho S, Inoue H. Slow and deep respiration suppresses steady-state sympathetic nerve activity in patients with chronic heart failure: from modeling to clinical application. Am J Physiol Heart Circ Physiol. 2014 Oct 15;307(8):H1159-68.

Howorka K, Pumprla J, Tamm J, Schabmann A, Klomfar S, Kostineak E, Howorka N, Sovova E. Effects of guided breathing on blood pressure and heart rate variability in hypertensive diabetic patients. Auton Neurosci. 2013

Kenney MJ, Claassen DE, Bishop MR, Fels RJ. Regulation of the sympathetic

nerve discharge bursting pattern during heat stress. Am J Physiol. 1998 Dec;275(6 Pt 2):R1992-2001.

Molkov YI, Zoccal DB, Moraes DJ, Paton JF, Machado BH, Rybak IA. Intermittent hypoxia-induced sensitization of central chemoreceptors contributes to sympathetic nerve activity during late expiration in rats.

J Neurophysiol. 2011 Jun; 105(6):3080-91.

Seals DR, Suwarno NO, Joyner MJ, Iber C, Copeland JG, Dempsey JA. Respiratory modulation of muscle sympathetic nerve activity in intact and lung denervated humans. Circ Res. 1993 Feb;72(2):440-54.

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