Across cultures, breath has always been understood as a bridge between the body and consciousness. Today, neuroscience and photobiology are revealing that breath profoundly influences the brain by regulating hemispheric activation, autonomic tone and internal photonic coherence. Breathing is simultaneously an electrical, emotional, photonic and energetic event. With each inhale, neural networks shift, blood flow redistributes, biophoton emissions change and the balance between cognitive and intuitive processing is altered. Breath influences many things.

Nasal breath determines brain hemispheric activation. It is also a powerful emotional regulator. Breath sets the tone for the sympathetic (“fight or flight”) and parasympathetic (“rest and digest”) nervous systems through a feedback loop involving the vagus nerve and mechanoreceptors in the airways. Slow, deep and exhale-focused breathing promotes parasympathetic dominance, while rapid, shallow breathing increases sympathetic activity. 

Breath affects fascia tension by either releasing or increasing tightness. Diaphragmatic breathing mobilises fascia, improving hydration and movement while shallow, stressed breathing (especially with neck muscles) creates tension, stiffness and restricted fascial layers, leading to pain, especially in the back, neck, and chest as the nervous system responds to stress. Deep, mindful breaths calm the nervous system, softening fascia, whereas fast, shallow breaths can increase fascial tone and trigger points, creating a cycle of restriction. 

In the yogic system, breath flows through three major nadis or energy channels: Ida, Pingala and Sushumna. Ida, the left channel evokes feminine expression. It’s lunar, cooling and intuitive sensing. Ida governs emotional states, is associated with silver/blue and the parasympathetic tone. The energy is inward and receptive. Pingala is the right channel. Viewed as masculine, solar and warming. Pingala is logical, active and associated with gold/red. It has a sympathetic tone and it’s energy is outward, expressive.

Modern light science beautifully parallels this as blue light physiology (Ida) impacting melanopsin activation, cognitive alertness, clear, cool emotional regulation and heightened introspection and awareness. Red/NIR light physiology (Pingala) promotes warming circulation, mitochondrial nourishment, emotional grounding and embodied vitality. The two systems, yogic and photobiological, describe the same underlying polarity. Cooling vs warming, cognitive vs somatic, intuitive vs active and blue vs red

Breath is the switch that determines which current is predominant. Most people naturally breathe predominantly through either left or right nostril at a time. This is known in physiology as the nasal cycle. Roughly every 60–120 minutes, subtle swelling and decongestion of the nasal tissues shifts airflow from one nostril to the other, with a brief period of balanced, dual-nostril breathing at the crossover.

The alternating flow of breath between the left and right nostrils occurs without conscious effort. It is a real, measurable process governed by the autonomic nervous system (ANS). When nerves activate the right nostril to take control of the breath, the brain switches to processing primarily through the left brain. When nerves switch breath to the left nostril, the brain process of the right brain dominate. This is not absolute, but statistically robust.

From a biomedical perspective, nostril dominance is controlled by the hypothalamus, which acts as a central regulator of autonomic rhythms. Inside each nostril are venous sinusoids (erectile tissue similar to that found elsewhere in the body). These tissues swell or shrink depending on autonomic input. When the tissue swells on one side, airflow is reduced and that nostril becomes “blocked.” The opposite side decongests and airflow increases. Sympathetic nervous system (SNS) activation leads to vasoconstriction and the nostril opens. Parasympathetic nervous system (PNS) activation leads to vasodilation and the nostril closes. The hypothalamus alternates this signalling rhythmically, typically every 60–120 minutes, though it can change with posture, activity, emotional state, illness or attention.

This switching is involuntary and continues during sleep. The brain itself is laterally organised. The two hemispheres are not redundant copies, they differ in how they regulate arousal, emotion, and bodily states. Broadly speaking the right hemisphere is more involved in autonomic regulation with a stronger influence on emotional tone, vigilance and bodily awareness. It is also more directly connected to parasympathetic modulation and vagal tone. The left hemisphere is more involved in goal-directed action with greater influence on sympathetic activation, speech, and linear processing and tends toward mobilisation and control.

Crucially, each hemisphere exerts greater influence over the opposite side of the body, including autonomic output. This means autonomic regulation is not globally uniform, rather it is laterally biased. Although often taught as a single system, the ANS has left–right differences in structure and influence. For example, the vagus nerve has left and right branches with different cardiac and visceral effects. Sympathetic chains run bilaterally alongside the spine, but do not fire identically. Organs receive asymmetric autonomic innervation (e.g., heart rate modulation differs by side). This creates slightly different baseline autonomic tone on each side of the body, what we might call functional asymmetry.

The nasal cycle makes lateral autonomic organisation visible. Each nostril is controlled by ipsilateral autonomic input. When sympathetic tone rises on one side, that nostril opens. The opposite side shifts toward parasympathetic dominance and the nostril closes. This alternating rhythm mirrors deeper lateral shifts throughout the body, not just in the nose. You can see this for yourself. When lying in bed on your side, keep your mouth closed and pay close attention to the airflow through your nostrils. When lying on your left side, you will notice breath in moves automatically to your right nostril. Try moving onto your right side and watch how breath changes as a result of the shift. You can also replicate this standing and leaning with pressure against a wall, alternating your side in turn. From a yogic perspective, this rhythm is the alternating flow of the nadi channels Ida and Pingala. Most human experience unfolds within this oscillation, activity and rest, thought and feeling, effort and release.

Yogic traditions teach that enlightenment arises when this oscillation resolves into sustained dual-nostril breathing. This state signifies the awakening of Sushumna, the central channel of integration. Rather than the nervous system swinging between opposites, energy flows centrally, producing nervous-system coherence, mental stillness without dullness, heightened clarity and presence with a felt sense of unity rather than polarity.

Importantly, this is not something to force. In classical yoga, permanent dual-nostril flow is said to emerge spontaneously when the nervous system is deeply regulated. In this view, simultaneous nostril breathing is not merely a breathing pattern; it is a biological marker of inner integration, where perception, energy and awareness move as one. While science does recognise dual (bilateral) nostril breathing as a real physiological state, it doesn’t interpret it as a permanent or special endpoint in the way yogic traditions do. Instead, science understands it as a transitional, integrative and context-dependent autonomic state.

Using airflow sensors, rhinomanometry and thermistors, researchers consistently observe brief periods where airflow is approximately equal through both nostrils. This is where neither nostril shows clear dominance. These moments occur naturally during transitions between dominance and during calm, parasympathetic states. They also occur during focused attention or meditation and occasionally during emotional resolution or safety. When both nostrils flow evenly, studies commonly observe reduced sympathetic arousal and increased parasympathetic tone. There is lower heart rate variability instability and increased vagal influence with reduced cortical “noise”. Science would describe this as a transient state of autonomic coherence.

Science doesn’t claim it is permanent since from a biological standpoint it is thought the nervous system is designed to oscillate. It is believed rhythmic switching prevents fixation and that permanent bilateral dominance would likely signal pathology, not enlightenment. Science sees continuous dual nostril breathing as unlikely, possibly maladaptive and not a goal state. Science doesn’t attach metaphysical meaning to biological events or experiences. Science doesn’t recognise that consciousness ascends or expands or that energy rises or enlightenment occurs. However, science identifies states where arousal decreases and integration increases. Network dominance softens and cognitive-emotional balance improves. Different language, same observation.

While cautious, science does recognise several distinct correlates of dual nostril breathing. Equal nostril airflow often correlates with reduced hemispheric asymmetry and increased interhemispheric coherence. More synchronised EEG patterns are observed. This doesn’t mean the hemispheres “merge” but dominance softens. Neuroscience frames this as reduced default-mode overactivity, increased global integration and less rigid predictive control. In plain terms, the brain becomes less defensive and more receptive.

Clinically, bilateral airflow states are associated with reduced anxiety and improved emotional tolerance. There is increased present-moment awareness and greater interoceptive clarity. This is why breath-based therapies are used in trauma and anxiety treatment. Science’s best current model is that dual nostril breathing reflects a moment of nervous-system integration, not a final state of consciousness. It sees it as a transitional state that is beneficial and repeatable but not something biology tries to “lock in forever.”

Yoga goes further and recognises simultaneous nostril breathing of both nostrils together is an achievable state indicative of when the integration of the brain system becomes whole again. Instead of switching between opposites, the nervous system settles into co-regulation, activation and rest held together. This is not neutrality or dullness. It is dynamic balance. The centre becomes active.

In yogic language, this moment marks the opening of Sushumna and Sushumna is the natural pathway of Kundalini. Rather than energy moving laterally between opposing pathways, it flows centrally. Translated physiologically, this corresponds to reduced autonomic conflict, coherent signalling between brain hemispheres, stable respiratory and cardiac rhythms and a sense of inner alignment. The system is no longer managing tension between opposites, it is organised as a whole.

When the nervous system is polarised, energy is constantly spent on switching states and maintaining readiness. It uses energy to inhibit one pathway while activating another. Simultaneous nostril breathing reflects a state where less energy is lost to internal opposition. Metabolic resources are freed for further repair, cognitive and emotional stability. Wholeness here means efficiency without suppression.

Crucially, sustained dual-nostril breathing is not achieved by mechanical effort. Forcing it creates strain and reintroduces polarity. Traditionally, it emerges spontaneously when emotional load is integrated and the nervous system feel safe. Attention becomes steady when energy availability is sufficient. In other words, the breath reflects integration rather than causes it. When both nostrils breathe together, the body is no longer negotiating between opposites. It is organised from the centre, whole, coherent and present.

In classical yoga, simultaneous nostril breathing was never treated as a breathing technique alone. It was understood as a physiological sign that a much deeper inner reorganisation had occurred, one associated with samadhi, liberation or enlightenment. The word enlightenment when broken down signifies moving from darkness to light.

Historically, enlightenment was not emotional bliss, spiritual status or constant pleasure. In yogic language, enlightenment meant freedom from compulsive identification with thought, emotion and sensation. It was perception no longer filtered through fear, craving or resistance. Awareness rested in itself rather than oscillating between opposites. Enlightenment was the end of internal fragmentation. It was described as non-dual awareness, stillness within movement and action without inner conflict. In biological terms, this corresponds to a system that is fully integrated rather than polarised.

Stripped of mysticism, yogic enlightenment can be understood as a state in which perception, energy and action arise from a unified centre rather than from competing internal drives. Or more simply, the end of inner division. Simultaneous nostril breathing mattered because it revealed this truth physiologically. When the system is whole, it breathes as one.

If we look toward synchronicity of the brain and breath as a way forward to a fully inhabited biology, we also need to to look further afield to the systems that can support this. These include a deep dive into the hemispheres of the brain that support thought and emotion.