Rhythmic Auditory Stimulation, Controlled Isometric Handgrip and One-Nostril Breathing (RACHO) as a Combined Non-Pharmacological Strategy for Adults with Hypertension: A Narrative Review of Physiological and Psychological Evidence

Abstract

Background: Blood pressure control in rural India remains poor, and a sizeable proportion of patients also report poor sleep, stress, anxiety or depressive symptoms. Rhythmic auditory stimulation, isometric handgrip exercise and slow left-nostril breathing are inexpensive practices that have each been studied for their effects on blood pressure or sleep, but they have not been evaluated together.
Aim: To review the evidence for each component of the RACHO package and to outline a mechanistic rationale for their combined use on blood pressure, sleep quality and psychological well-being in adults with hypertension.
Methods: PubMed/MEDLINE, Scopus, Web of Science, the Cochrane Library and Google Scholar were searched up to October 2026 for meta-analyses, systematic reviews, guidelines and relevant trials. Findings were grouped by component and outcome and appraised narratively.
Findings: In a network meta-analysis of 270 trials, isometric exercise training produced the largest fall in resting blood pressure of all exercise modes (systolic -8.24 mmHg, diastolic -4.00 mmHg). Slow-paced breathing reduced systolic pressure by roughly 5-7 mmHg, and among pranayama techniques the left-nostril forms appeared most promising. In hypertensive patients, music interventions lowered blood pressure and anxiety and depression scores and improved Pittsburgh Sleep Quality Index scores. Evidence supporting continuous white noise for sleep was of very low certainty. The three components appear to act on overlapping pathways, including sympathetic outflow, baroreflex sensitivity and vagal tone, peripheral resistance, stress reactivity and sleep.
Conclusion: RACHO is a low-cost package with a plausible biological basis that can be practised at home and delivered through rural primary care. Randomised trials that measure blood pressure, the Pittsburgh Sleep Quality Index and the Depression Anxiety Stress Scales-21 together are required to establish whether the combination is more effective than its individual components.