Independent research has documented many positive effects of the Sudarshan Kriya on many health parameters. Presented below are summaries of a few significant findings.

Effect on Cortisol

Several studies have demonstrated significant falls in cortisol levels. In one study, blood cortisol, known as the ‘stress hormone', was measured in 21 individuals, 35-50 years of age. Regular Sudarshan Kriya and Pranayama (SK&P) practitioners (Group 1) were compared with beginning practitioners (Group 2) during their SK&P sessions. The beginning practitioners were also measured before learning SK&P, while listening to classical music (Group 3). Among beginners, the fall in cortisol levels was significantly greater during SK&P than when listening to classical music, suggesting that SK&P produces a better relaxation response.

The significant further fall in serum cortisol levels, during, and following SK&P, among beginning, and regular practitioners, suggests that regular practice of SK&P develops greater levels of resilience to stress.

Effect on Blood Lactate

Blood lactate is another biochemical measure of stress. Participants in police training constitute a highly stressed group. They undergo intense physical, and emotional training daily. Blood lactate was measured in 10 such individuals, both before learning SK&P, and after the first session. There was a significant fall in lactate levels after SK&P, suggesting that it induces a state of relaxation.

Effect on Antioxidant Enzymes

Free radicals can react with oxygen and cause oxidant damage, contributing to many diseases, including cancer, and such cardiovascular diseases as heart disease, and stroke. To counteract these free radicals, the human body has a defence system in the form of antioxidant enzymes. A study was conducted to assess the effect of SK&P on antioxidant enzymes. Levels of three major antioxidant enzymes - superoxide dismutase (SOD), catalase, and glutathione - were all found to be significantly higher in SK&P practitioners than in the matched control group, which suggests that people who practice SK&P have an improved antioxidant status, and an enhanced defence against oxidant damage.

Effect on Immune Function

Natural killer (NK) cells are believed to be important in the body's defence against new, and recurring cancers. NK cells are the surveillance cells of the immune system, and are capable of destroying tumour cells as well as infected cells. NK cells were counted in the peripheral blood of three groups: SK&P practitioners, normal individuals not practicing SK&P, and cancer patients in remission. NK cells were significantly higher (p<0.001) in the SK&P group than in either non-practicing individuals or in cancer patients in remission. The cancer patients then learned SK&P. After 3-6 months of regular practice, there was a significant increase in the cancer patient' NK cell count.

Effect on Blood Cholesterol

Psychosocial stress is a major contributor to hypertension, and coronary heart disease (CHD). In CHD, deposits of LDL cholesterol, fat, and other substances on the arterial walls slow or block the flow of blood, resulting in heart malfunction. A study was conducted to assess the cholesterol levels of individuals before they learnt SK&P, as well as after 7 and 45 days of regular practice. Significant drops in total cholesterol, and LDL (harmful) cholesterol, as well as increases in HDL (beneficial) cholesterol were observed. These findings suggest that SK&P improves the blood cholesterol profile, and that regular practice may therefore prove to be an effective tool in preventing and arresting hypertension and CHD.

Effect on Depression

SK&P has been shown to have a 68-73 per cent success rate in the treatment of depression, regardless of severity. Relief from depression, determined by psychiatric evaluation, and standard psychiatric measures (Beck Depression Inventory, Hamilton Rating Scale for Depression, and others), was experienced within three weeks. Published studies suggest that SK&P may be as effective as Imipramine, a standard antidepressant.

Effect on Post-Traumatic Stress Disorder

SK&P has been used to relieve post-traumatic stress disorder (PTSD) in thousands of survivors of mass disasters. In a study of 180 survivors of the 2004 Southeast Asian Tsunami, SK combined with the Breath-Water-Sound Program (an 8-hour yoga breath course) significantly reduced symptoms of PTSD and depression on psychological tests (PTSD Checklist, Beck Depression Inventory, and Global Health Questionnaire). Improvements occurred in four days and were maintained at three-month and six-month follow-ups. These practices have the potential to provide rapid psychological relief to large populations following mass disasters when conventional healthcare systems are overwhelmed.

Improved Brain Function

To study the long-term effects of SK&P on brain function, EEG (electroencephalogram) changes were recorded in 19 SK&P practitioners outside of the practice of SK&P, and compared with EEG patterns of 16 controls (doctors and researchers who did not practice SK&P, yoga, or meditation). Significant increases in beta activity were observed in the left frontal, occipital, and midline regions of the brain in the SK&P practitioners, as compared to controls (p<0.05). These results are interpreted by neurologists as indicative of increased mental focus/heightened awareness in SK&P practitioners.

EEG activity was also studied during the practice of SK&P in five females of similar age, socio-economic ,and educational backgrounds. This study found an increase in EEG alpha activity, with interspersed persistence of beta activity. This indicates a state of relaxation co-existing with heightened alertness.