In September 2018, James Nestor and Anders Olsson embarked on an intriguing self-experiment. Both men call themselves ‘Pulmonauts,’ dedicated to exploring the transformative power of breathing to enhance physical, mental, and emotional health.
The self-experiment was guided by Dr. Jayakar Nayak, a researcher at Stanford University. The setup was very simple. For 10 days, both men would breathe exclusively through their mouths. For another 10 days, they would breathe only through their noses.
Throughout the experiment, Dr. Nayak conducted regular measurements, tracking blood pressure, pulse rate, heart rate variability, body temperature, and pH levels. Their sleep was filmed at night to document occurrences of snoring and sleep apnea.
For the first 10 days, their noses were effectively blocked to ensure no nasal breathing was possible. James described quite vividly how Dr. Nayak inserted silicone nose clips deep inside his nasal passages. It was far from enjoyable, and, as James said, “things would only get worse from here.”
Before delving into the results, it is important to note that nearly 40% of today’s population suffer from chronic nasal obstruction, and about 50% of those are habitual mouth breathers, with women and children being the most affected.
The health impact of mouth breathing is tremendous. With their noses blocked, Nestor’s snoring increased by 1,300% on the first night, lasting a total of 75 minutes. Olsson’s results were even worse. He went from no snoring at all to a staggering four hours of it. Both participants also experienced sleep apnoea events … times when breathing is interrupted or stops for seconds or even minutes.
As the days went by, the consequences of mouth breathing became increasingly clear, and by the end of the 10 days, it had taken a toll on their health. Measurements showed elevated stress hormone levels, substantially increased blood pressure, and reduced heart rate variability. Both men struggled with concentration, sleep disturbances, and a general sense of weakness and exhaustion, accompanied by post-exercise shakiness and nausea. The experience was, as Nestor described it, “an utter disaster.”
For the next 10 days, however, the two Pulmonauts shifted exclusively to nasal breathing.
The transformation was dramatic.
Almost immediately, the negative effects began to reverse. Snoring decreased by about 85% during the first night and stopped entirely after just two nights. Sleep apnoea events completely disappeared. Blood pressure dropped back to healthy levels, and both men reported feeling more energetic, focused, and mentally clear. Even their stationary bike performance at the gym improved by 5–10% over the 10-day period.
This experiment powerfully demonstrated the profound difference that breathing through the nose can make, not just in terms of reducing snoring and sleep apnoea, but also in restoring overall health and well-being. Nasal breathing is far healthier because it filters, warms, and humidifies the air, protecting the lungs from irritants and pathogens. It also promotes better oxygen absorption by maintaining optimal levels of carbon dioxide, which enhances overall respiratory and cardiovascular health.
Following the experiment, James Nestor went on to write his bestselling book Breath, where he shares remarkable stories about how breathing can shape a healthier life. Beyond his advice to maximize nasal breathing, another key suggestion stood out for me: to breathe slower and less.
On average, humans are considered medically “normal” when they take 12–20 breaths per minute, with an average air intake of about half a liter per breath. However, according to Nestor and other breathing experts, we’ve become not only a culture of overeaters but also over-breathers.
Newer research, along with proven ancient breathing techniques, suggests that optimal breathing happens at a rate of about 5-6 complete breaths per minute. This much slower, lighter breathing is quite different from what we’re used to. To practice this type of healthy slower breathing, Nestor recommends a simple app – (https://pacedbreathing.app/ ).
I’ve personally used it for the past few weeks and would highly recommend it. You can set the breathing intervals precisely to the target of 5.5 seconds per inhale and 5.5 seconds per exhale, with the app gently vibrating to signal when to breathe in and out. I’ve found it to be a wonderful tool that can even be used during video calls, with the slower pace of breathing being deeply calming, which lowers stress levels.
This month, I’d like to invite you to pay closer attention to how much you’re breathing through your nose. If nasal breathing feels difficult at first, don’t be discouraged. Nestor highlights several examples in his book of people gradually rebuilding their nasal breathing habits. As he says, “if you don’t use it, you lose it.”
I encourage you to try using the app to practice slower, lighter breathing at the recommended rate of 5.5 seconds per in and exhale. It may feel very challenging at the start, but there’s no downside. It’s completely free, and the more you practice, the calmer, clearer, and more relaxed you will feel.
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