Understanding the Science Behind Breath, Emotion & Yoga

by Dr. Katharina Austermann — Anandam Yoga School

Introduction

We all know the feeling: your breath becomes shallow when you’re stressed or anxious, and effortlessly deep when you feel calm and safe.

This isn’t a coincidence — it’s physiology. Your diaphragm, the primary muscle of breathing, is deeply intertwined with your emotional state. It responds instantly to how you feel, and through the breath, it also influences how you feel.

In this article, we explore the science behind the diaphragm, the nervous system, and how yoga uses this connection to cultivate emotional balance.

The Diaphragm: More Than a Breathing Muscle

The diaphragm is a large, dome-shaped skeletal muscle that contracts downward during inhalation and relaxes upward during exhalation.

While its movement is controlled by the phrenic nerve (C3–C5), diaphragmatic motion strongly influences physiological systems involved in emotional regulation, including:

• thoracic pressure changes
• baroreceptor activation
• lung stretch receptor signaling
• heart-rate variability (HRV) through vagal activation

This means the diaphragm is not controlled by the vagus nerve — but its movement is one of the strongest mechanical ways to activate vagal pathways.

Supported by research:

Bordoni & Marelli (2016) describe the diaphragm as part of a “respiratory–emotional system,” noting that changes in stress and affective states influence its tension and movement.

Citation: Bordoni, B., & Marelli, F. (2016). The diaphragm and emotions: embryological, anatomical and physiological review. Frontiers in Medicine, 3(43).

How Emotions Shape Your Breathing Pattern

Emotional states produce measurable changes in respiratory pattern:

• Stress / anxiety: rapid, shallow, upper-chest breathing
• Sadness: irregular or sigh-dominant breathing
• Calmness: slow, full diaphragmatic breathing

These patterns are directly tied to limbic system activity — especially the amygdala and insula.

Supported by research:

A study by Boiten (1998) shows that emotions reliably alter breathing patterns, including rate, depth, and posture.

Citation: Boiten, F. A. (1998). The effects of emotional behaviour on components of the respiratory cycle. Biological Psychology, 49(1-2), 29–51.

Vagus Nerve Activation — The Bridge Between Breath & Emotions

Although the vagus nerve does not innervate the diaphragm, diaphragmatic breathing strongly activates the sensory nerves of the vagus nerve.

This happens through:

• lung stretch receptors
• baroreceptors in thoracic cavity
• changes in heart-rate variability
• thoracic–abdominal pressure shifts

Slow breathing increases vagal tone, which sends “calm signals” to the brain, reducing emotional arousal.

Supported by research:

• Brown & Gerbarg (2005) showed that slow yogic breathing significantly increases vagal activity and reduces anxiety and depression.
• Porges’ Polyvagal Theory explains how breath influences emotional regulation through vagal pathways.

Citations: Brown, R. P., & Gerbarg, P. L. (2005). Sudarshan Kriya yogic breathing in the treatment of stress, anxiety, and depression. Journal of Alternative and Complementary Medicine, 11(4), 189–201.

Porges, S. W. (2011). The Polyvagal Theory: Neurophysiological foundations of emotions, attachment, communication, and self-regulation. Norton.

Additionally, Ma et al. (2017) found that an 8-week diaphragmatic breathing program significantly decreased cortisol and negative mood.

Citation: Ma, X., Yue, Z., Gong, Z., et al. (2017). The effect of diaphragmatic breathing on attention, negative affect and stress in healthy adults. Frontiers in Psychology, 8, 874.

Modern research confirms: Slow diaphragmatic breathing increases vagal tone, reduces cortisol, and improves emotional regulation.

Yoga recognized this thousands of years ago — long before modern neuroscience gave us the language.

Why Yogic Breathing Is Emotionally Transformative

Traditional yogic practices — such as Nadi Shodhana, Ujjayi, and slow exhalation breathing —
use diaphragmatic motion to regulate the nervous system.

Through mechanical vagal stimulation, they:

• reduce sympathetic activation
• increase heart-rate variability
• support emotional stability
• improve internal sense of safety
• strengthen interoceptive awareness

Supported by research:

Jerath et al. (2006) describe slow yogic breathing as a method for increasing parasympathetic activity and reducing emotional reactivity.

Citation: Jerath, R., Edry, J. W., Barnes, V. A., & Jerath, V. (2006). Physiology of long pranayamic breathing: neural respiratory elements may provide a mechanism that explains how slow deep breathing shifts the autonomic nervous system. Medical Hypotheses, 67(3), 566–571.

Your breath is not just a tool — it is a direct line to your emotional brain.

Diaphragm Awareness in Yoga Practice

During practice, the diaphragm often mirrors emotional state:

• In challenging poses → breath becomes shallow, diaphragm stiffens
• In grounding poses → breath deepens, diaphragm softens
• In restorative work → diaphragm movement becomes smooth and expansive

A simple self-awareness practice:

1. Lie down comfortably.
2. Place one hand on your belly, one on your ribs.
3. Breathe slowly and let the lower hand rise first.
4. Lengthen your exhalation gently.

This immediately increases vagal tone and creates emotional regulation.

During yoga asana practice, pay attention to how your diaphragm behaves:

• It may tighten during difficult or stressful postures.
• It opens and becomes spacious during grounding poses.
• It mirrors the mental state you bring onto the mat.

When the diaphragm is tight (stress response):

• Breath stays mostly in the upper chest
  
• Lower ribs feel stiff and don’t expand easily
• A subtle pressure or tightness under the sternum
• Belly feels pulled in or braced
  
• Breathing feels a bit effortful or restricted
  
• Body holds tension around the waist, sides, or lower back
  
• Emotional tone: restlessness, alertness, or unease
  

 When the diaphragm is soft (relaxation response):

• Breath feels slow, deep, and effortless
  
• Lower ribs expand gently in all directions
• Belly softens and rises with the inhale
• A feeling of spaciousness around the lower chest and abdomen
• Exhale becomes longer and smoother
  
• Whole midsection feels warm, released, and open
  
• Emotional tone: calm, grounded, balanced

Conclusion: The Breath as Emotional Medicine

Your diaphragm gives you real-time feedback about your inner world.
When the breath is shallow, the nervous system is tense.
When the breath is deep and slow, the body returns to balance.

By learning to work with your diaphragm consciously, you’re not just improving your breath — you’re cultivating emotional stability, resilience, and inner peace.

This is where the science of the body and the philosophy of yoga meet.

Further Learning with Anandam Yoga School

If you’re curious about the deep connection between anatomy, yoga, and emotional health,
we explore these topics extensively in our Yoga teacher trainings.