?? Breath and Depth: How Freediving Affects Your Body & Mind

The Neuroscience, Biology and Expansion of Consciousness Induced by Deep Dives

Hey friends,

This week’s Nina’s Notes is a collaborative article I wrote with Amánda Efthimiou on the neuroscience, biological changes and meditative state induced by freediving.

Amánda and I have been talking about writing a collab article for some time, and originally we had discussed writing on neuroscience and music, because Amanda just published her research with Amanda Marie Cardinale on "The Role of Music in Psychedelic-Assisted Therapy" exploring music's neurobiological, cultural, and therapeutic significance in psychedelic-assisted therapy in Psychedelic Medicine Journal.

We ended up choosing the topic of neuroscience and consciousness during free diving because of Amánda’s personal experience and my growing interest in it after watching the insane Netflix Documentary The Deepest Breath.

The human body is truly unbelievable in how it can perform during this extreme sport, and how it can be a fast track to altered states of consciousness and how fundamental integration of this experience is.

If you want to learn more about integration, check out the my interview with Amánda on the Nina’s Notes Podcast.

Enjoy!

Amánda Efthimiou is a transformation coach, keynote speaker and facilitator that explores the nexus of consciousness, technology, and the future of wellbeing to regenerate self and society. With an MSc in Neuroscience, she focuses on the integrative effects of plant-based medicines, architecting personal transformations by bridging traditional knowledge systems with scientific insights. A dedicated student of nature, she previously directed a nonprofit aimed at supporting the preservation of bio-culture and indigenous territories in the Amazon basin. Founder of INTEGRA Amánda consults for health and wellness companies, creating spaces for professionals to harness and integrate their innate intelligence and accelerate transformation across people, business, and planet.

?? In this note:

• ?? Breath and Depth: How Freediving Affects Your Body
• ?? Humanity and the Deep Ocean
• ?? The 10,000 Year Clock

?? Breath and Depth: How Freediving Affects Your Body

What is Freediving?

Freediving is an underwater diving technique where divers hold their breath and dive without using scuba tanks.?

Freedivers rely entirely on their lung capacity and ability to control their breath to explore underwater environments.

How Long Can Freedivers Stay Underwater?

For untrained individuals, the average breath-hold time is typically around 30-90 seconds.

Recreational freedivers can hold their breath for two to four minutes with proper training and relaxation techniques.

Professional and elite freedivers can hold their breath for four to six minutes.

What Impact Does Freediving Have On Your Body?

Freediving can have both positive and potentially negative effects on the body.

On the positive side, the cardiovascular system can experience enhanced heart efficiency, blood circulation, and oxygen utilization developed through controlled diving practices.?

Freedivers see increases in lung capacity and improvements in the body's ability to exchange oxygen and manage carbon dioxide levels.?

The nervous system also experiences changes, particularly through the development of the mammalian dive reflex, which allows individuals to remain calm and controlled under extreme physical stress.

Unlocking the Mammalian Dive Reflex Through Freediving

The Mammalian Dive Reflex is an involuntary mechanism that occurs when we are submerged in water, particularly when the face is cooled by water.?

We evolved this reflex to conserve oxygen and survive underwater for extended periods of time.

Freedivers can learn to control this natural response in order to stay underwater longer.

When triggered, the mammalian dive reflex causes several immediate physiological changes:

1. Bradycardia (slowed heart rate) - A freediver’s heart rate can drop as low as 10-25% of the normal resting rate. This reduction helps to conserve oxygen and directs blood flow to critical organs like the brain and heart.
2. Peripheral Vasoconstriction - The blood vessels in the extremities to constrict, reducing blood circulation to arms and legs, and redirecting blood and oxygen to vital organs, such as the heart, lungs, and brain, in order to preserve core body functions.
3. Blood Plasma Redistribution - As pressure increases, blood plasma moves from the extremities to the chest cavity this prevents lung compression to maintain their volume at increased water pressure, which is crucial for survival in deep waters.

This redirection of blood flow, slow heart rate and oxygen optimization helps freedivers stay underwater longer and more safely.

Neurological Adaptations in Freediving

Oxygen Deprivation Tolerance

Freediving depends on the ability to tolerate low oxygen levels, called hypoxia tolerance, while maintaining consciousness and control.?

Advanced freedivers can stay focused and maintain motor control, even when their oxygen levels get dangerously low.

To do this, freedivers train their brains to handle oxygen stress and use oxygen more efficiently. This training helps delay the body's natural panic response and lets them stay underwater longer.

The part of the brain that adapts during this training is the medulla oblongata, located in the brain stem. It has sensors called chemoreceptors that monitor the oxygen and carbon dioxide levels in the blood.

By strengthening the link between these sensors, the respiratory control centers, and the autonomic nervous system, freedivers are able to control their breath for longer.

The Meditative Dimension of Freediving

Many freedivers describe their dives as a meditative experience.?

The focus on breath, the silence of the deep, and the weightlessness can lead to a profound sense of presence and calm.?

This state is similar to deep meditation, where brainwave patterns shift and there's increased coherence between different brain regions.

Deep meditation works by bringing the mind into a state of focused attention and relaxation, often achieved through practices like breath control.?

During a meditative state, the prefrontal cortex becomes less dominant. This allows for reduced self-referential thought patterns and a letting go of everyday concerns, cultivating feelings of inner peace and clarity.?

Neuroscience shows deep meditation increases alpha and theta brainwave activity. Alpha waves support relaxation while theta waves enhance creativity and introspection.?

Freediving mirrors these effects.?

The controlled breathing before a dive reduces stress and shifts the body towards a parasympathetic state.?

During the dive, hypoxia and the mammalian dive reflex trigger theta wave activity similar to the deep meditation brainwave shifts.

The silence and sensory deprivation in the water heightens the meditative experience and the resulting state of focus and presence it induces.

Similarly to deep meditation, freediving can be considered an altered state of consciousness, a state characterized by significant changes in thought, sensorial perception, and awareness.

Breath-holds of freediving can stimulate an altered state through hypoxia-induced euphoria and sensory deprivation.?

The combination of physiological changes with the immersive underwater environment blurs the lines between the self and the surrounding world.?

In unexpected ways, freediving becomes a potent avenue for accessing altered states and exploring the depths of human consciousness.?

Professional freedivers have reported profound changes in perception after their dives, including a sense of euphoria, rapture, and mental clarity that stays with the body for hours or days after a dive.

Some divers describe an expanded sense of self, a unifying connection with life, and an increased appreciation and harmony with the natural environment.?

Anecdotal accounts highlight experiences of gratitude, clarity, and even a sense of spiritual awakening and a surge of self-discovery.

Similar to other altered states of consciousness, the meditative and transformative nature of diving often sparks introspection, leading many to explore themes of physiological and mental resilience, and connection to the underwater world.?

For both amateur and professional freedivers, integrating the dive is key.?

Integration

Beyond measurable results like depth and time, freediving emphasizes harmony between mind and body, self and nature.?

Integration transforms this temporary state into a lasting way of being.?

For some, a structured framework for understanding and processing the dives and grounding techniques can support a sense of purpose and continuity between the underwater experience and daily life.?

This process of integration starts with intentional reflection after the dive, such as writing the emotions, sensations, and insights that came up.

Practices like mindfulness and meditation can help carry the calm and focus experienced underwater into your daily routine.

Connecting with a community of freedivers or seeking mentorship from experienced freedivers can provide a supportive space and to share and contextualize these powerful experiences.?

Physical grounding activities, like yoga, can also help you reconnect with your body after diving.

By taking this holistic approach, you can transform the profound experiences of freediving into meaningful and sustainable personal growth.

The Risks of Freediving on the Body

Physical Risks

While our bodies' natural physiology can be trained to allow freedivers to push boundaries in ways that seem almost superhuman, they do not come without risks.

Blood pressure fluctuates, core body temperature drops, and adrenaline surges.

These are not minor adjustments, but big shifts in bodily function that can push biological systems to their absolute limits.

Lung squeeze, barotrauma, and the terrifying possibility of shallow water blackout are risks waiting for any diver who has not mastered their technique.

Repeatedly testing these limits can even lead to neurological challenges and potential cardiovascular strain in freedivers.?

The brain and heart, those critical organs that keep us alive, are not invincible. They can be worn down by repeated oxygen deprivation.

Professional training is absolutely essential, and you should never practice freediving techniques alone.

Psychological Risks

Freediving also presents psychological risks, especially for those unprepared to manage the intense mental demands of the activity.?

The deep focus and potential altered states of consciousness experienced during dives can trigger anxiety, disorientation, or even panic, both underwater and after resurfacing.

Without proper integration, these experiences may lead to emotional distress or difficulty processing the profound shifts in perception that freediving may elicit in the diver.

While for safety reasons a freediver’s number one rule is to never dive alone, the solitary nature of a diving experience can potentially exacerbate feelings of isolation. Particularly if they lack a supportive community or framework to share and contextualize their experiences.?

This being said, mental preparation and post-dive reflection are essential for maintaining the diver’s psychological well-being.

Amánda Shares Her Free Diving Experience

My own journeys with free-diving have shown me just how profound an altered state the experiences can be. Amidst the technically challenging descents in the water and the need to be fully alert to my body’s own limitations, I have encountered the thin line between life and death.?

The silence of the deep demands my full presence.?

Every heartbeat feels magnified and every moment is immediate.?

Without the distraction of the surface, I felt the dive transform into an experience of raw clarity, my humble human life distilled to its essence.?

In that stillness, I knew of a connection that existed to something greater than my individual body. As if the ocean itself were a representation of the interconnectedness of all life, while mirroring the paradox of fragility and resilience within the human existence.?

To me freediving is a bonafide altered state of consciousness experience. Not just a physical challenge but a mental and spiritual journey, where presence becomes both a necessity and a gift.

The deep focus and surrender required underwater have taught me how to be more present above the surface with my community, family, neighbors, strangers, and professionally with colleagues and clients.?

Freediving has shown me the value of pausing to truly listen to one another. It’s helped me approach each moment with clarity of intention.?

It has also given me the courage to share my inner journey publicly, to teach others about the balance between effort and surrender, and to guide them toward greater self-awareness and connection.?

Where to find Amánda Argot Efthimiou:

• Website
• INTEGRA
• Recíproco Psychedelic Integration course?
• Instagram?
• LinkedIn?
• Newsletter?

?? Content of the Week

Humanity and the Deep Ocean by James Nestor

Rating: ★★★★★

One of the best YouTube videos I’ve watched recently.

I was totally glued to the TV watching James Nestor’s talk where he dives into the details of freediving, covering more than the thrill, but also covering the changes in senses and human biology.

At around minute nine, Nestor shares a video of freediver Guillaume Néry and talks through all the physiological changes Néry’s body experiences as he dives into Dean's Blue Hole in the Bahamas.?

At 100ft deep, Nestor explained that Néry’s lungs would be the size of two baseballs and his heart rate could slow to just 7 beats per minute. A heart rate that slow should not be enough to sustain life, but in a way that we do not yet understand, it keeps us alive in the depths.

James Nestor is the author of Breath: The New Science of a Lost Art which I wrote about two years ago in Nina’s Notes #8.

James Nestor’s talk was recorded live five years ago at The Interval Bar, Cafe, & Museum in San Francisco as part of the Long Now Foundations “Conversations at The Interval” Salon Talks.

The Interval is still hosting their Salon Talks today. Make sure to check their schedule next time you are in San Francisco.

Want to learn more about The Long Now Foundation??

Check out their website and YouTube Channel.

?? Check This Out

A clock that will tick for 10,000 years.

The Long Now is building the 10,000 year clock. They chose 10,000 years because that is the timescale of civilization. And they call this, “The Long Now.”

I went to The Interval Bar many times when I lived in San Francisco, and was always impressed by the prototypes for the 10,000 year Clock and the beautiful working planetary display in the entrance.

Now the clock has been built and its design follows, Long Now Board Member and Clock Inventor, Danny Hillis’ vision for it:

“I want to build a clock that ticks once a year. The century hand advances once every 100 years, and the cuckoo comes out on the millennium. I want the cuckoo to come out every millennium for the next 10,000 years.”

Want to visit the clock?

Well…that might be a bit difficult. It is tucked inside of a mountain in West Texas, and extremely ambiguous directions are given on the Clock's Frequently Asked Questions page.

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