Several mechanisms are involved
Abnormal low heart rate variability (HRV) is associated with both medical and psychiatric disorders. HRV biofeedback is a recently developed technique that aims to modulate HRV in ways that have beneficial effects on mental and emotional functioning. The magnitude and specific characteristics of HRV are related to the body’s ability to adapt to stress. Low HRV generally corresponds to relatively greater susceptibility to stress. HRV is probably related to several underlying mechanisms that work together to ensure the healthy ‘adaptive’ functioning of the body’s cardiovascular system. Abnormal HRV signifies that the body’s stress response is not optimal resulting in potentially more harmful effects of chronic stress and increased risk of stress-related medical or mental disorders such as heart disease, depressed mood, generalized anxiety, panic disorder and post-traumatic stress disorder (PTSD). HRV biofeedback is a technique that has grown out of this insight, and aims to optimize HRV so that individuals can better manage stress and have fewer and less severe diseases caused by chronic stress.
Regular HRV biofeedback training reduces stress and improves general well-being
Findings of a few studies done to date suggest that chronically anxious patients who undergo HRV biofeedback training experience significant improvements in general emotional well-being and reduced baseline anxiety. In one study healthy adults (45 total subjects) were randomized to an emotional self-management program versus a wait list group that received no treatment (McCraty 1998). Significant reductions in cortisol levels and increased coherence in heart rate variability were found in individuals in the experimental group but not in the comparison group. The experimental group reported significant decreases in measures of guilt, hostility, burnout, anxiety and stress. These psychological changes correlated with significant reductions in serum cortisol levels and beneficial increases in measures of coherence in heart rate variability.
In one 4-month controlled trial the most of a group of 29 police officers who trained in biofeedback techniques based on HRV reported significantly greater improvements in baseline anxiety compared to 36 officers who were assigned to a wait-list group and received no treatment. In another study (McCraty 2009) that enrolled 75 correctional officers, those individuals randomized to a group that received training in emotional self-regulation and HRV biofeedback reported significant reductions in overall stress, had a more positive outlook, and had significant reductions in physiological indices of stress including reduced cortisol levels, reduced resting heart rate and blood pressure. Individuals in the treatment group had significant increases in productivity, motivation and perceived support.
Findings of a 5-week open study suggest that daily HRV biofeedback training, vigorous physical activity and mindfulness meditation may be equally effective for stress reduction in healthy adults (Van der Zwan 2015).
More studies are needed
Large long-term prospective sham-controlled studies are needed to confirm the magnitude and type of physiological and psychological benefits of HRV biofeedback, and to optimize HRV biofeedback protocols addressing different medical and mental health problems.