Insomnia is consistently more prevalent among women, middle-aged and older adults, shift workers, and patients with coexisting medical and psychiatric disorders. Although insomnia has a greater overall prevalence in adults, the nature of insomnia interacts with age, such that sleep maintenance difficulties are more common among middle-aged and older adults, whereas sleep initiation difficulties are more frequent among younger adults. A worldwide study found that the highest prevalence rates of insomnia were in Brazil (79.8%), followed by South Africa (45.3%), Eastern Europe (32%), Asia (28.3%) especially in India(12.7%), and Western Europe (23.2%). Treatment of insomnia should be individualized based on the nature and severity of symptoms and should occur after other causes have been considered, diagnosed, and treated. Treatment options for insomnia that do not involve drugs include relaxation techniques, cognitive behavioral therapy, stimulation control therapy, paradoxical intention therapy, sleep restriction therapy, temporal control therapy, better sleep hygiene, and moderate exercise.

Yoga is a practice that includes Eight Limbs such as spiritual concepts (yamas and niyamas), body postures (asanas), breathing manipulations (pranayamas), concentration/focusing techniques (dharana), meditation (dhyana) and surrendering (Samadhi). Among Pranayama is the Fourth Limb. Pranayama is a breath control practice. In Sanskrit term, Prana+ayama means Vital energy or Life force. Different pranayamas cause unique physiological and cardiovascular responses in individuals. Swarodaya Vigjnan, from the Vedic language, means "knowledge of the nasal cycle" (swara = sonorous sound created by the airflow through the nostrils in the nasal cycle, udaya = functioning state). When practicing pranayama, or the yoga breathing method, dominance of the left nostril (called "ida" swara) triggers parasympathetic activity. The nasal cycle is influenced by the amounts of neurohormones and catecholamines in the blood as well as the tonic activity of the limbic autonomic nervous system, which is regulated by the hypothalamus. 

The peripheral nervous system’s autonomic nervous system controls involuntary physiological functions like blood pressure, breathing, and heart rate. Stimulation of the left brain hemisphere causes sympathetic activity, while stimulation of the right hemisphere causes parasympathetic activity. One of the many essential biological processes that the autonomic nervous system regulates is sleep and wakefulness. Heart rate variability (HRV) is a variable which is widely used to assess the autonomic regulation of the heart by measuring the changes in the cardiac rhythm through time. Previous research has demonstrated that forced unilateral nostril breathing or specific nostril yogic breathing causes selective stimulation of the contralateral hemisphere, as indicated by alternating lateralization of plasma catecholamines and relative increases in the contralateral hemisphere’s electroencephalogram amplitude. Breathing practice increases the vagal tone of the sinoatrial (SA) and atrioventricular (AV) node and also improves baroreceptor sensitivity, although at a breathing rate of six breaths per minute. HRV has circadian periodicity with significant alterations during the transition from wake to sleep and across sleep cycles.

Very few studies are available in the literature that shows the effect of particular pranayama on Heart Rate Variability (HRV) with underlying conditions. So we planned to elucidate the effect of chandranadi pranayama on Heart Rate Variability among primary insomnia, making this research a valuable contribution to the field –A Randomized Controlled Study.