The Science of Breath: Types of Pranayama and Scientific Approach to Practice

                 The Science of Breath: Types of Pranayama and Scientific Approach to Practice

Prof. Yamini Bhushan Tripathi, PhD Biochemistry and Diploma in yoga

                                Chief Scientist & CEO, Yamini Innovations LLP, Varanasi, India

Former Dean of the faculty of Ayurveda, Institute of Medical Sciences, Banaras Hindu University, Varanasi-221005, India, yamini30@gmail.com

 

We breathe roughly 22,000 times a day. Yet, how often do we realise that each breath holds the remote control to our blood pressure, heart rate, and stress levels? Long before modern clinical trials, ancient seers identified this profound biological connection. Today, cutting-edge neurophysiology, sports medicine, and chronobiology fully validate what they termed Pranayama.

Universal Resonance: Shifting from Ritual to Biology

Breath control transcends geography and culture. While the methods differ, the underlying objective—calming the autonomic nervous system—is woven into the core practices of all major global traditions. Like in Hinduism, Trikal Sandhya, in Islam,  Ruku and Sajdah during Namaz; in Christianity, the stillness maintained during Contemplative Prayer; in Buddhism & Jainism, practices like Anapanasati and Preksha Dhyana. All of them utilise mindful breath observation to systematically down-regulate emotional centres in the brain. They mirror the deep, rhythmic respiration that calms autonomic arousal, optimise cerebral blood flow and stimulate vagal afferents. In trikal saddhya, mantra chanting establishes a resonant rhythm to synchronise the heart and brain, and during Namaz, the physical postures help in blood circulation to the brain.  

The Three Pillars of Breath Regulation: It is important to note that Pranayama is not only a physical exercise of the lungs or respiratory system, but a gateway to balance the autonomic nervous system, by balancing the sympathetic and parasympathetic nervous systems. Classical texts describe three distinct phases in pranayama, altering our respiratory cycle:

1. Puraka (Inhalation): A conscious, controlled intake of oxygen that expands the lungs and temporarily increases sympathetic drive.
2. Kumbhaka (Retention): Holding the breath either internally (Antar) or externally (Bahir). This induces localised pressure changes and triggers the baroreflex loop.
3. Rechaka (Exhalation): A prolonged, deliberate release of breath. Physiologically, stretching the exhalation phase is the fastest shortcut to slowing down the heart via the vagus nerve.

 

3 Functional Classes and 4 Major Types of Pranayama

However, in common practice, pranayama is being taught on TV and other online modes, only as inhalation-exhalation. It is because wrongly practised “kumbhak” may be harmful to patients with BP and cardiovascular disorders. Based on modern neurophysiology, pranayama can be categorised into three distinct functional classes depending on their impact on the Autonomic Nervous System (ANS). Their timing and conditions of performing also vary according to circadian physiology.

Before I proceed further, I would like to explain the Autonomic Nervous System (ANS). It can be defined as the body’s internal "auto-pilot" network. It regulates all the involuntary functions—such as your heartbeat, blood pressure, and digestion—that happen continuously without your conscious thought. This network is governed by two opposing yet complementary forces:

• The Sympathetic Force (The Accelerator): This is the body's alert mechanism. It is governed by the brain's control center, the Hypothalamus, which constantly processes incoming data from our 5 sense organs. When your senses perceive stress, workload, or danger, this force immediately steps in to accelerate your heart rate and elevate your blood pressure to prepare you for action.
• The Parasympathetic Force (The Brake): This is the body's healing and recovery mechanism. It is governed primarily by Vagal Activation (the Vagus Nerve). When you practice deep breathing, rest, or meditate, this force steps in to apply the biological brakes—lowering your blood pressure, calming your heart, and activating your digestion and cellular repair.

The Pranayama, broadly divided into 3 classes, balances these two forces.

Class 1: Relaxing/Parasympathetic Activators. It should be done to relax the body or to stabilise the overactive mind, like in conditions of anxiety.

1. Anulom-Vilom / Nadi Shodhana (Alternate Nostril Breathing)

• How to do it: Close the right nostril, inhale through the left. Close the left, exhale through the right. Reverse the process.
• The Science: Practised in a 1:2 ratio (e.g., inhale for 4 seconds, exhale for 8 seconds without retention), it balances the sympathetic and parasympathetic nervous systems, improving overall Heart Rate Variability (HRV) [1].

2. Bhramari (Humming Bee Breath)

• How to do it: Close your ears with your thumbs, eyes with your fingers, inhale deeply, and make a sustained "humming" sound as you exhale.
• The Science: The vibrations from humming dramatically boost the endogenous production of Nitric Oxide (NO) in the nasal sinuses by up to 15-fold. Nitric oxide acts as a potent vasodilator, relaxing blood vessels and lowering blood pressure [2].

Class 2: Energising/Sympathetic Stimulators. It is practised in stage of depression with feelings of low energy.

3. Kapalbhati & Bhastrika (Bellows Breath)

• How to do it: Kapalbhati involves passive inhalations and forced, rhythmic exhalations. Bhastrika involves rapid, forceful inhalations and exhalations.
• The Science: These techniques stimulate the sympathetic nervous system, increase metabolic rate, elevate mitochondrial activity, and improve cognitive alertness [3].

Class 3: Cooling/Thermoregulatory. As the name indicates, this is practised for thermoregulation, when having a feeling of heat shocks.

4. Shitali & Sitkari

• How to do it: Inhaling air through a rolled tongue (Shitali) or through clenched teeth with the tongue pressed behind them (Sitkari), followed by normal nasal exhalation.
• The Science: This draws cool air over the vascular mucosa of the mouth, acting directly on the hypothalamus to lower core body temperature.

Chronobiology: Matching the Right Breath to the Right Time

Pranayama Type	Ideal Time Window	Neurobiological Effect
Bhastrika & Kapalbhati	Morning (Empty Stomach)	Clears morning lethargy, activates metabolic processes, and optimizes lung volume.
Anulom-Vilom	Anytime (Morning, Afternoon, Evening)	Balances hemispheric brain activity and stabilizes autonomic fluctuations.
Bhramari & Shitali	Evening / Before Bedtime	Suppresses Muscle Sympathetic Nerve Activity (MSNA), triggers melatonin release, and prepares the body for deep sleep [4].

 

Ayurvedic concept of “tridosh” balance, as per circadian rhythm: It is important to know that there is a natural shift of predominance of Vata, Kapha and Pitta as a 4-hour cycle, starting from 2 AM up to 2 PM. The same sequence of cycles repeats every 12 hours of the day. Pranayama of different classes are also synchronised with this cycle, as they regulate brain activity, thermogenesis and digestion, heartbeats, and blood pressure.

Clinical Safety Rules for Hypertension and Heart Disease (IHD/CVD)

If you suffer from High Blood Pressure or Ischemic Heart Disease, pranayama can be a therapeutic medicine—but only if you avoid dangerous pressure spikes.

• Kumbhaka (Breath Retention) is Strictly Forbidden: Forcing yourself to hold your breath raises intrathoracic pressure (the Valsalva Maneuver). This cuts off venous return to the heart temporarily, followed by a severe rebound spike in blood pressure. Hypertensive and IHD patients must practice purely continuous, unhindered breathing.
• Avoid Fast-Paced Kapalbhati/Bhastrika: Rapid, jerky movements can trigger an acute sympathetic spike, putting unnecessary stress on coronary arteries.
• The Safe Prescription: Stick to Slow-Paced Breathing (SPB). Inhale for 4 seconds and exhale smoothly for 6 to 8 seconds. This activates the Respiratory Sinus Arrhythmia (RSA) loop, gently lowering blood pressure and shielding the heart from stress [5].

Workplace Bio-Hacks: Managing Acute Stress, Anger, and Fatigue

You do not need a yoga mat to reset your nervous system. These quick, desk-friendly exercises can be performed directly from your office chair:

• 1. For Brain Fog, High Workload, or Mental Fatigue:
• The Fix: Sit straight, close your eyes, and perform 5 slow rounds of Bhramari.
• The Result: The surge in nitric oxide and vagal stimulation instantly calms the amygdala (the brain's panic center) and restores executive function in the prefrontal cortex.
• 2. For Acute Anger, Irritation, or a Panic Surge:
• The Fix: Implement the "Prolonged Exhalation" rule. Inhale through your nose for 3 seconds, purse your lips, and blow the air out slowly for 7 to 8 seconds as if blowing out a candle.
• The Result: This acts as an immediate physical brake on the heart, dropping an elevated heart rate within seconds.
• 3. For the 3 PM Post-Lunch Slump/Lethargy:
• The Fix: Close your left nostril and breathe exclusively through your right nostril (Surya Anuloma Viloma) for 10 to 12 breath cycles.
• The Result: This selectively shifts autonomic balance toward left-brain hemispheric dominance, increasing alertness without the need for caffeine.

The Bottom Line (Conscious Biology Perspective): Pranayama is not just an ancient ritual; it is a real-time software update for your Autonomic Nervous System. By altering the depth, rhythm, and duration of your breath, you can directly influence your internal physiology. It is achieved by activating the vagal stimulation and by inhibiting the production of cortisol. It brings the body from “alert mode” to “resting mode”. It balances the “Mind-body connect”, “Gut-brain axis”, which are important for your wellness and prevention of NCDs (non-communicable diseases) like obesity, diabetes, heart disease, and high blood pressure.

Respect your body's boundaries, tailor the practice to your medical status, and use your breath to live a balanced, healthier life.

📚 Scientific References:

1. Saoji, A. A., et al. (2019). Effects of regulated alternate nostril breathing on autonomic functions: A systematic review. Journal of Alternative and Complementary Medicine, 25(3), 254-268.
2. Weitzberg, E., & Lundberg, J. O. (2002). Humming greatly increases nasal nitric oxide. American Journal of Respiratory and Critical Care Medicine, 166(2), 144-145.
3. Novaes, M. M., et al. (2020). Effects of Yoga Respiratory Exercises (Pranayama) on Clinical and Autonomic Parameters. Frontiers in Psychiatry, 11, 627.
4. Pramanik, T., et al. (2009). Immediate effect of a slow pace pranayama on cardiovascular parameters. Journal of Alternative and Complementary Medicine, 15(3), 293-295.
5. Russo, M. A., et al. (2017). The physiological effects of slow breathing in the healthy human. Breathe, 13(4), 298-309.