Nadis

Nadis form the energetic circulatory system of the subtle body, much as blood vessels serve the physical body. The three primary nadis run along the spine. Sushumna, the central channel, runs through the spinal column and is the pathway through which kundalini energy ascends. Ida (lunar, cooling, feminine) and Pingala (solar, heating, masculine) spiral around the Sushumna, crossing at each chakra. When Ida and Pingala are in balance, prana can enter the Sushumna — a prerequisite for deep meditation and spiritual awakening. Most people have one channel dominant at any time, which yogic practice aims to equalize. Alternate nostril breathing (Nadi Shodhana) is specifically designed to balance these two channels. Blockages in the nadis are believed to cause both physical and psychological illness. Yoga asanas, pranayama, and meditation work to clear these channels, allowing prana to flow freely throughout the subtle body.

The earliest detailed account of the nadi system appears in the *Shvetashvatara Upanishad* (~400–200 BCE) and the *Chandogya Upanishad*, which describe channels (*nāḍī*, Sanskrit "tube, channel") through which life-force moves. The systematised three-channel model (Ida, Pingala, Sushumna) and the 72,000-nadi figure are codified in the later Yoga Upanishads — particularly the *Yoga-Yajnavalkya* (~10th–12th century CE) and the *Hatha Yoga Pradipika* of Svatmarama (~15th century CE), which devotes chapter 3 to nadi purification through pranayama. Tantric texts including the *Shiva Samhita* (~17th century CE) extend the model. The Chinese meridian (*jingluo*, 經絡) system documented in the *Huangdi Neijing* (~2nd century BCE) addresses a related but historically distinct mapping of subtle channels; whether the parallel reflects shared cultural transmission or independent development is debated in the comparative scholarship (Geoffrey Samuel and Jay Johnston, *Religion and the Subtle Body in Asia and the West*, 2013). Modern Western introductions trace through Swami Vivekananda's *Raja Yoga* (1896), the Bihar School of Yoga publications, and B.K.S. Iyengar's *Light on Pranayama* (1981).

Practice Nadi Shodhana (alternate nostril breathing) for 10 minutes daily — Iyengar's *Light on Pranayama* (1981) gives the canonical detailed instructions and is the most rigorous English reference. The ratio to learn first is the standard 1:1:2 (inhale 4 / hold none / exhale 8) for a few weeks before adding retention. Notice which nostril is more open at different times of day — the nasal cycle is a documented physiological phenomenon (alternating turbinate engorgement, roughly every 60–90 minutes per Eccles 1996 in *Acta Otolaryngologica*) and the yogic interpretation maps onto it. Sit upright, with the spine clear of the chair back, and use the right hand in Vishnu mudra (thumb to right nostril, ring finger to left). Avoid retention work if pregnant or with uncontrolled hypertension.