In my 20s, like many others who find that their mind is poisoning their life, I discovered meditation. Though for a long time I found it impossible, I liked all the encouragements to stop paying attention to my thoughts, because I feared and loathed many of my thoughts. I was less impressed by the suggestion that – to quote the teacher at a retreat I attended – my breath was ‘the most powerful force in the Universe’ or that ‘all wisdom starts with proper breathing’. Breathing? I thought. That is how I will escape this flirtation with what feels like madness? By breathing? Sat stiffly, failing to follow the most powerful force in the Universe as it moved through my nostrils, I inwardly scoffed, warming myself with my own incredulity.

Five years later, like the once-foolish novice in many a spiritual parable, my annoyance has given way to a degree of understanding. I’m no yogi, and my practice is scattered, improvised and private. But I consider my breathing constantly. In doing this, I flirt with the madness less brazenly, and less often.

Cut out of the chest and held up to the light, the human heart is shiny as a ripe, purple grape. The lungs are shaped like a pair of heavy wings. It all looks very damp, very vivid, and very strong. From the day that we are abandoned by the umbilical, until the day when the last fires will wave to us, this fleshy equipment stands between us and nonexistence. And yet: unless (until) it malfunctions, we tend to barely consider it.

However. This base layer of our anatomy is hooked up to the whole physical network from which consciousness blooms. And for millennia, people – mainly the people my meditation teacher was channelling – have tapped options other than autopilot for their simple, subtle power. As is so often the case, Western science is catching up, and so is culture: breathing, you might have noticed, is in vogue. In fact, according to Vogue magazine itself, breathing is ‘the new yoga’. This is partly a fad, one more potential solution to the pervasive unease of the everyday. But all fads have their kernel of truth, and this kernel is real: breathing is at the core of us, and anything at the core of us can be harnessed.

Once, nothing breathed. Life originated in anoxia, a complete absence of oxygen, and persisted this way for almost 2 billion years: minuscule, microbial, ocean-bound. It might have carried on this way for 2 billion more years, but for the emergence of an algae called cyanobacteria. This was the first organism to produce oxygen through oxygenic photosynthesis – the conversion of light into energy, with oxygen expelled as waste. Feeding off the limitless energy source of the Sun, cyanobacteria bloomed blue-green across the surface of the oceans. The upstart, previously minor gas oxygen proliferated. Once surface stores of iron and sulphur couldn’t soak it up anymore, oxygen flooded the atmosphere, and this new abundance triggered a fall in methane levels that plunged the planet into an ice age that lasted 300 million years.

This drastic change in the makeup of our atmosphere didn’t, as previously thought, trigger a mass extinction. But it did radically alter the nature of organic life. Aerobic respiration releases 16 times more energy than older forms of metabolism. It produced so much energy – was so ‘exergenic’ – that it enabled multicellular life. Fuelled by oxygen, an unknown bacterial ancestor evolved into mitochondria, the oxygen-processing component of the complex cells that make up almost all eukaryotes. From here on out, ‘gas exchange’ would define advanced life. Anaerobic organisms retreated to low-oxygen niches in the extreme deep of the ocean. Higher up, the seas blossomed with sponges, anemones, molluscs and the rest of that otherworldly bazaar that, right this second, somewhere, is captivating a scuba diver.

As the biology of gas exchange evolved, skin was superseded by gills, and gills were superseded by rudimentary lungs. After this long underwater gestation, around 500 million years ago, ‘aquatic-to-terrestrial transition’ began. Eukaryotic life moved from ocean to land, and proto-reptiles evolved, with stunning slowness, into mammals and birds. Birds evolved their own method of gas exchange, involving a series of air sacs lodged throughout the body and bones. In mammals, the lungs became the powerhouse, existing at the centre of a process that goes like this: on inhale, the diaphragm flattens downward and the intercostal muscles lift up the ribs, expanding the volume of the lungs. As volume increases, air pressure decreases relative to the atmosphere, and air rushes in. Mammalian lungs are covered with millions of microscopic balloons called alveoli; through their infinitesimally thin walls, the oxygen in air is picked up by the red blood-cell protein haemoglobin and carried to the ever-ravenous cells. Carbon dioxide travels in the opposite direction, transferred by the alveoli to the soon-to-be-exhaled air. On exhale, the diaphragm and intercostal muscles relax. The decrease in lung volume results in increased pressure relative to atmosphere, and so the air rushes out. Thus, a single breath. Repeat until death.

Anyone who has ever tried hallucinogens knows that taking a long, greedy breath can be like dropping a paint bomb into your visual cortex

The mammalian respiratory system includes the complex structure of the airways, an element of which is the larynx. Around a quarter of a million years ago, there emerged a type of primate whose larynx lies lower down the neck than the other great apes, enabling it to vocalise. Much later, in one of its countless tongues, this primate would label itself Homo sapiens. Human respiration, meanwhile, went on adapting to environmental pressures. Last year, the Bajau ‘sea nomads’ of southeast Asia, who have been free-diving on a daily basis for thousands of years, were found to possess enlarged spleens that help them hold their breath for remarkable stretches of time.

Despite valiant efforts, our early investigations into breathing were a grasping in the dark. The Ancient Egyptians thought that all bodily fluids passed through the heart, even urine and semen. Hippocrates had no idea that the lungs were involved in breathing, and Aristotle thought that they were merely a cooling mechanism for the heart. The great physician Galen thought that we absorbed air through our skin. It wasn’t until the 17th century that our understanding of breathing advanced in any real way. In the 1660s, Robert Boyle constructed his famous air pump, and demonstrated that sucking the air out of a sealed chamber made the sorry animal contained inside it shuffle off its mortal coil.

A century later, Joseph Priestley discovered that an unknown gas did the opposite: sustain both candles and animal life. And before he was guillotined during the French Revolution, the nobleman Antoine-Laurent de Lavoisier proved that this gas was a chemical element existing in air, and named it oxygen. In the 1870s, Eduard Pflüger demonstrated that the real action of oxygen consumption happens down at the intracellular level, not just in the blood or lungs. Other advances followed, bringing us to the scientific picture that I have paraphrased here, while mindlessly going through thousands of litres of oxygen, and without once stopping to give thanks to cyanobacteria for kicking off the whole parade.

But breathing is more than rote biology. Yes, it can happen unconsciously, as it does every night for the hours that we are asleep. But unlike other physiological processes – digestion, say, or menstruation – breathing can also be brought within our direct control. And the effects of such control can spread through the rest of the anatomy.

The simplest way that breathing can be manipulated is straightforward and physical. In his autobiography, the late Johan Cruyff – one of the greatest soccer players of all time – describes how, during his time coaching the Dutch team Ajax, he brought in an opera singer who specialised in breathing techniques to ‘help the players get the maximum return on every inhalation and exhalation. That’s very important in top-level sport.’ Cruyff is right. Breathing slower and deeper improves arterial oxygenation, cardiac output, pulmonary gas-exchange efficiency, and other things that are important to a human body in a state of physical exertion. This functional approach to breathing well has a long lineage, particularly in the West. Galen might not have understood respiration, but in 175 CE he recommended various sorts of diaphragmatic rituals to athletes, especially those eating ‘an abundance of pig’s flesh’.

However, the potential for marginal athletic gains is not the reason why conscious breathing is currently having a moment. When Tony Robbins, the god-emperor of American self-help, declares that: ‘Once you pay attention to your breath and master its true power, you master your life and your outcomes,’ he is talking about more than maximising lung or muscle power. He is talking about that slippery thing we call consciousness.

Anyone who has ever tried hallucinogens knows that taking a long, greedy breath can be like dropping a paint bomb into your visual cortex. That there is a broader link between breath and perception – that our most basic physical process can be a portal to metaphysical discovery – is an ancient idea. The ancient Greek word pneuma, the Sanskrit prāṇa, the Chinese Qi, the Hebrew nefeš, and the Polynesian mana all mean ‘breath’ or ‘air’ and also something like ‘spirit’ or ‘vital force’. Partly, this is a simple association between breathing and being alive, as in the book of Genesis, when God ‘formed man of the dust of the ground, and breathed into his nostrils the breath of life; and man became a living soul.’ But in non-Western traditions, there is a different belief: that breathing correctly can lay a foundation for maintaining wellbeing, and gaining wisdom.

Baha-ud-Din Naqshband Bukhari, a prominent 14th-century Sufi, declared that: ‘The more that one is able to be conscious of one’s breathing, the stronger is one’s inner life.’ In the Taoist text the Zhuangzi, it is said that ordinary men breathe ‘from their throats’, but that the sage breathes ‘from his heels’ (with his whole body). The meditation teacher I encountered on a retreat, meanwhile, was true to her Buddhist association: one of the Buddha’s best-known discourses (the Ānāpānasati Sutta) is dedicated to 16 styles of meditative breathing, a practice that, according to the Zen master Thich Nhat Hanh, can enable us to ‘look carefully, long, and deeply, see the nature of all things, and arrive at liberation’. In all forms of Buddhist meditation, the breath is used as an anchor with which to steady the ship of incessant and corrosive cogitation; endlessly directing your attention there aims at a ‘one-pointedness’ of mind that promises an end to suffering. Possibly the best-known form of conscious breathing, meanwhile, is prāṇāyāma, one of the eight limbs of yoga. You might be familiar with the experience of going to a class in need of a decent workout, and finding yourself cross-legged on the floor, placing a thumb over alternating nostrils for long stretches of time.

With our breath, we conduct a sort of internal, fleshy semaphore

This is conscious breathing’s more beguiling side: its capacity to interact with emotion, the psyche, perhaps even the spirit. A century of philosophical globalisation has seen a broadly Eastern conception of conscious breathing move from the esoteric to the mainstream. Today, certain techniques are so mainstream that your doctor is just as likely to recommend them as your hippie sibling. Hillary Clinton has said that, along with Chardonnay, yogic breathwork helped her get over losing the 2016 US election to Donald Trump.

The science of how breathing alters consciousness goes all the way down. Like any organism, our chief evolutionary drive – spreading our genes – requires that we don’t die. Not dying requires that we constantly respond to our physical environment, so that we don’t walk off a cliff or between the jaws of a sabre-toothed tiger. The critical task of survival is the focus of the nervous system. In humans, as in all vertebrates, our central nervous system, located in the brain and spinal cord, gathers information from our peripheral nervous system, which absorbs sensory information from the rest of us, and then communicates motor impulses back out. All of this happens very fast. As the name suggests, the autonomic nervous system is that long-fibred section of the peripheral nervous system that regulates our basic, involuntary processes. It makes us squint in sunlight, sweat in a sauna, salivate at the sight of a freshly halved nectarine, and so on. If we are not doing so wilfully, it also regulates our breathing.

The autonomic nervous system is further broken down into the sympathetic nervous system and the parasympathetic nervous system. On a breath-to-breath basis, these two operate to create the heart’s one-two rhythm that you hear when you rest your ear on the chest of a lover. They are antagonistic in the broadest sense. The sympathetic nervous system exists to prime us for physical action; it fires up, for example, shortly before we wake up. Under conditions of stress, it responds by conjuring the cascade of neuronal and hormonal responses known as the fight-or-flight response. Everyone knows the feeling: your heart picks up, your mouth goes dry, your mind is nothing but brittle reaction.

Meanwhile, the parasympathetic nervous system evolved to perform in conditions where a threat to survival is absent. When it is engaged, we enjoy a warm dump of the neurotransmitter acetylcholine, and the body’s slower processes occur: sleep, sexual arousal, immune activities, proper digestion, toilet necessities. Specific processes aside, when the parasympathetic nervous system is online, our cognition clears. Thinking slows down, and focus is enhanced.

Here is where breathing comes in: one of the major areas of parasympathetic nerve supply is the vagus nerve (from the Latin for ‘wandering’). This cranial nerve is the longest in the autonomic network, running from the brainstem right down to the abdomen via most of our organs. Branches of the vagus nerve interface with our respiratory system (and larynx). Diaphragmatic breathing, especially with an exaggerated exhale, stimulates this wandering messenger of our body’s relaxation centre. With our breath, we conduct a sort of internal, fleshy semaphore. The autonomic nervous system understands this airy signalling, and lets the parasympathetic nervous system go to work – a process whose underlying neurology was mapped for the first time in 2017, in experiments with mice. With nothing but the breath, you can ask your body and very being to slow down, relax, be not afraid.

Slow, deep breathing is probably the oldest folk remedy on Earth. It is so ingrained in us that people will find themselves doing it instinctively ahead of public speaking, or while enduring the pain of a wound being disinfected. Such careful breathing is always associated with an experience of cooling, of decelerating. It works in almost any scenario where the mind is being catapulted by the body, and we want control. When we are on the precipice of weeping, and want our cheeks to stay dry. When we are approaching orgasm too fast. When we want desperately not to vomit. The list goes on.

While we do this intuitively, conscious breathing can be perfected through best practice and technique. The specifics vary, but the basics are: lie or sit. (If you’re sitting, straighten your back like you would for a photo, but be prepared to let your belly inflate outwards, like you never would for a photo.) Over a count of five, breathe in through your nose, letting the air balloon all the way to your navel. Pause for a second. Over another count of five, breathe out through your mouth. Do this for five or 10 minutes. That’s it. This approach aligns with the view of the European Respiratory Society that ‘autonomically optimised respiration would appear to be in the band of six to 10 breaths per minute, with an increased tidal volume that is achieved by diaphragmatic activation’. (Tidal volume is the amount of air a person inhales during a normal breath.) The conscious impact is subtle, but if you’re lucky, it’s there: a reduction in the white noise behind your eyes. A slight stillness in the flesh.

Scientific research on conscious breathing is hard to gather up. Some of it is published in leftfield journals, and studies mix terminology (deep, slow, controlled, yogic, abdominal). But caveats aside, hard findings are there. All the good research accepts that the chief physiological mechanism is the interface of conscious breathing with the parasympathetic nervous system. The range of claimed effects is bewildering in scope.

Here is what seems solid: there is some evidence that yogic breathing lowers blood pressure, improves diabetic symptoms, can alleviate depression, and can help with asthma and the management of migraines and chronic pain. There is good evidence that yogic breathing reduces inflammation and boosts the immune system. Conscious breathing appears to be associated with moderate improvements in many areas of cognition, especially attention and memory retrieval. A recent study revealed that it ‘remarkably enhances retention of a newly learned motor skill’. There is robust evidence that deep breathing reduces stress and any form of anxiety.

Cast out into the more isolated or less robust studies, and there is some evidence that deep breathing can help with poststroke aphasia, atrial fibrillation, heart failure, ADHD, chronic neck-pain, menopausal symptoms, abstention from smoking, recovery from bypass surgery, wellbeing in breast-cancer patients, and more. Some of the claims made are truly grand. Though it sounds like pure woo-woo, a study from the august Annals of the New York Academy of Sciences found that yogic breathing ‘might reduce the incidence and progression of cancer’.

Strange but true: breathing is keeping you alive, but it’s also killing you

The only way to read this fireworks display of benefits is to conclude that intentional deep breathing is good for you – all of you. And that, though they had grander aspirations than the medicalised West, the ancient mystics were right: the breath has far-reaching powers. In Tibetan Buddhism, the esoteric ‘Yoga of the Dream State’ aims to expose a practitioner to the reality of māyā; the illusory, dreamlike nature of everyday, egocentric perception. One way to comprehend māyā is via ‘the power of breath’. This involves sleeping ‘on the right side, as a lion doth’, and engaging in a two-handed process of blocking the nostrils and pressing the throat while you ‘let the saliva collect in the throat’. And if you’re trying to comprehend māyā by visualising yourself as the female deity Vajrayogini, breathing can help here as well. At dawn, seven rounds of ‘pot-shaped’ belly-breathing should be practised.

Interestingly, in these older traditions, it isn’t only about breathing slowly and deeply. In Kundalini yoga, there are practices where one suspends the breath altogether for longer and longer stretches. In an appendix to his book The Doors of Perception (1954), Aldous Huxley describes how such a practice ‘permits the entry into consciousness of experiences, visionary or mystical, from “out there”’. In 1837, an ascetic yogi used meditative breathing to help him survive being buried alive for 40 days. Allegedly. Such otherworldly efforts are similar to Taoism’s so-called embryonic breathing, where the breath is made so sedate that a feather held under the nose remains still – one of a vast set of cryptic practices aimed at redirecting sexual energy to achieve immortality.

Interestingly, the reverse – hyperventilating – also has its spiritual side. Yogic breathing includes the practice of kapalabhati, or ‘breath of fire’. A more adventurous teacher might also have introduced you to this at the start of a yoga class. You sit up tall, then breathe quick and hard and loud through your nose, snapping your stomach on the exhale. In yogic parlance, this type of conscious breathing promotes ‘detoxing’ and ‘inner cleansing’.

To a skeptic, these aren’t encouraging descriptors. But they receive vague validation through one of the most famous breathing specialists of our current moment, the eccentrically charming Wim Hof. This extreme athlete’s breathing technique includes deep breathing, but also periods of controlled hyperventilation. In a small study, Hof’s approach was shown, rather amazingly, to increase human resistance to acute E coli exposure. Paradoxically, Hof’s work suggests the opposite of deep breathing might also help to boost immunity. This is hard to reconcile with the rest of the scientific picture as it stands. After millennia of scrutiny, a full understanding of the breath eludes us.

Strange but true: breathing is keeping you alive, but it’s also killing you. As in all species, human gas exchange is fine-tuned so that uptake of oxygen occurs at precisely the level required, but not a molecule more. Why? Because oxygen is a fantastic fuel for meeting metabolic demand – but it is also toxic. Every second, the mitochondria in our trillions of cells are converting blood-borne oxygen into energy. This primordial chemistry takes a heavy toll. In all of us, to quote the journal Comprehensive Physiology, it is ‘cumulative cellular oxygen stress’ that makes ‘senescence and death inevitable’.

Strange, that breathing can be at once so everyday, so forgettable – and also the material plane on which all of life and death manifests. In not exactly the sense that my meditation teacher meant it, the breath is without doubt, from the human perspective, the most powerful force in the entire Universe. Yes, conscious breathing is a fad; yes, there is something faintly ridiculous about people learning how to do something that they do every second of their lives without even thinking about it. But as discovered by diverse spiritual traditions, spread over thousands of years and divided by thousands of miles, it is worth thinking about.

Though I’ve remained an on-again-off-again meditator, developing the instinct to remember my breath comes to my rescue almost every day. My motivation for going on that meditation retreat persists; my thoughts can still move too fast, and they can be awfully loud. But heaving my attention away from the surging river of consciousness back to my body – back to those older parts of me that in ancient incarnations of my DNA were doing their mineral, material work long before evolution conjured up the chattering forebrain – helps me to turn down the noise. Whenever my mind starts to trample me, whenever I feel my perception turning skittish and clawing, I go to the base of my stomach, and I make it the limit of my thought. It is always there, this respite, this remembrance that everything layered on top cannot possibly be as important as the miracle of my body keeping me from death. There is a perception in this, I suppose, of something like māyā. Some vast, secret slipstream, behind the sound and fury.

Mine is a specific use of conscious breathing, but they all come down to this: to connect with the breath is to connect with what is most vital in you, as a creaturely thing. Whatever your suffering, if you find yourself needing to feel more at home in this world and in this body that carries you through it, let a lungful of oxygen fill you up. Make a practice of it, if you like. There’s a good chance it will help. Come back to the core. All of us are but borrowing our oxygen, for a while.