Heart Rate Variability and Emotional Health

What is Heart Rate Variability?

Most of the time, our heartbeat seems to be fairly consistent - almost like a clock, ticking along at a regular pace. That said, there are situations when it’s quite obvious that our heartbeat changes, for example in response to physical demands (such as playing sport or running up the stairs), when we feel fear and our threat response is triggered, or during pleasant states of arousal, like feeling exhilarated or elated. We notice our heartbeat speeding up in the presence of physical or emotional demands, or in states of excitement, and then slowing down when those those things are no longer present.

However, what might not be obvious - or even detectable to us - is that there are slight fluctuations in the frequency of our heartbeat all the time, sometimes just fractions of a second that we couldn’t notice ourselves. For example, if a person has a heart rate of 60 beats per minute, the time intervals between each beat won’t be exactly the same. This fluctuation in heart rate - both the more noticeable changes and the subtle, undetectable ones - is called heart rate variability (HRV). In simple terms, heart rate variability is the measure of the variation in time intervals between each heartbeat.

How the autonomic nervous system influences HRV

This variation is controlled by the autonomic nervous system - the part of our nervous system that regulates many bodily functions automatically, without conscious control. These include changes in blood pressure, heart rate, breathing, and digestion.

The autonomic nervous system has two main components:

1) The sympathetic branch increases arousal and prepares us for action. There is a release of adrenaline which increases the speed and intensity of our heart rate, raising blood pressure to ensure our muscles receive enough blood and oxygen if action is required. Physically and psychologically, we feel energised and ready to respond. In situations of perceived threat, this activation prepares us to optimise survival - hence the term fight or flight.

2) The parasympathetic branch reduces arousal and allows us to rest and restore when action is not needed. It activates our natural calming responses, including slowing the heart rate and lowering blood pressure. Often referred to as rest and digest, parasympathetic activation helps us feel physically and psychologically calmer as levels of arousal decrease. A major component of this system is the vagus nerve, which sends signals that slow the heart rate.

HRV and adaptability

The heart rate variability that occurs in a healthy nervous system that shifts between sympathetic and parasympathetic activation reflects our body’s capacity to adapt to what’s happening around us. When heart rate is highly variable, it indicates that our nervous system can respond flexibly - increasing arousal when helpful and calming arousal levels when appropriate.

There is also a natural shift between sympathetic and parasympathetic influence each time we inhale and exhale. This phenomenon is called respiratory sinus arrhythmia. When we inhale, heart rate naturally increases as parasympathetic influence briefly withdraws. When we exhale, parasympathetic activity resumes, slowing the heart rate once again. In this way, HRV can also be understood as a reflection of autonomic balance.

Modern stress and autonomic imbalance

Unfortunately, many of us are not in autonomic balance. We may remain in states of sympathetic activation for longer than is helpful, largely due to the nature of modern-day stress.

Sometimes we do need to act quickly - for example, to move out of the path of an oncoming car. However, most stresses we face today don’t require us to physically fight or flee, yet our brain and body may still prepare us for action. In many ways, our nervous system has not evolved at the same pace as the types of stress we now experience.

Modern stressors tend to be more chronic and enduring, such as financial pressures, emotional concerns, relationship difficulties, health worries, or the demands that come from work or education.

Being stuck in this state often means we experience reduced parasympathetic activation and less variability in heart rate, which can lead to reduced resilience. In other words, our brain and body may struggle to adapt to changing situations because they are less practised at returning to a calmer baseline state.

Why is heart rate variability important for mental health?

Research indicates a link between HRV and mood and anxiety. Depression, PTSD, and a range of anxiety disorders - including panic disorder, OCD, generalised anxiety disorder, and social anxiety - have all been associated with reduced HRV.

This makes sense, as reduced HRV reflects lower adaptability in the face of change. While adaptability is often thought of in physical terms, psychological adaptability is equally important. Emotional health is reflected in our ability to acknowledge and work through our emotions, and to gently return to a grounded baseline afterwards.

Reduced psychological flexibility and difficulties with emotional regulation are both linked with lower HRV. Social engagement may also be negatively affected, alongside reduced activity in the prefrontal cortex - the brain region that supports deliberate, flexible responses. These features are commonly seen across depression, anxiety, and trauma-related difficulties.

For example, in anxiety disorders, it may be difficult to disengage from worry and hypervigilance, leading to chronic sympathetic activation and reduced parasympathetic activity. As a result, heart rate remains elevated and HRV decreases. Researchers suggest that improving HRV may help reduce symptoms of depression, anxiety, and PTSD.

How can we improve heart rate variability?

Improving HRV involves developing flexibility between states - practising both activation and relaxation to help the nervous system become more adaptable.

This can be done through therapy in a top-down way, by exploring different ways of interpreting and responding to experiences that can reduce emotional distress or increase helpful arousal when needed.

HRV can also be improved from the bottom up by changing our physical state to influence our emotional state. Slowing the breath activates the parasympathetic system and slows the heart rate, which can be helpful when we feel overly activated. Research suggests that breathing at a slower pace can improve HRV, with around six breaths per minute often cited as particularly effective.

Some studies indicate that breathing with a longer exhale - for example, a 1:2 inhale-to-exhale ratio - may further enhance HRV. Activities that naturally involve longer exhales, such as singing, chanting, and humming, can also support this process.

Breathing is one way to balance autonomic arousal, but we can go further. Any activity that involves periods of increased heart rate followed by recovery supports flexibility in the autonomic nervous system. This might include exercise that alternates effort with rest. (If you have concerns about your heart, or health in general, it’s always advisable to speak with your GP before starting a new exercise programme).

HRV and yoga therapy

The yoga practice taught as part of the Yoga Therapy 8 Week Course places a specific emphasis on improving HRV by sequencing practices to include intentional increases in heart rate and arousal, followed by periods of rest and calming practices. This structured approach supports the development of nervous system flexibility and can contribute to improved emotional wellbeing.

Developing resilience through nervous system flexibility

It can be tempting to assume that we should never feel activated, but heightened states are not inherently negative. They can feel positive - such as when we feel excited or energised - and stress responses can also help us grow and navigate challenges.

When activation is appropriate to the situation and we practise calming ourselves when needed, we strengthen our ability to return to baseline. This builds resilience in the nervous system and supports greater emotional tolerance and psychological flexibility.

Interested in learning more?

If you’re interested in exploring this for yourself, feel free to get in touch to discuss how yoga therapy, or an integration of yoga therapy skills and psychotherapy, may be helpful for you. You can read more about one-to-one work and the 8-week course here.

References

Chalmers, J. A., Quintana, D. S., Abbott, M. J. A., & Kemp, A. H. (2014). Anxiety disorders are associated with reduced heart rate variability: a meta-analysis. Frontiers in psychiatry, 5, 80. https://pubmed.ncbi.nlm.nih.gov/25071612/

Ge, F., Yuan, M., Li, Y., & Zhang, W. (2020). Posttraumatic stress disorder and alterations in resting heart rate variability: A systematic review and meta-analysis. Psychiatry investigation, 17(1), 9. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6992856/

Russo, M. A., Santarelli, D. M., & O’Rourke, D. (2017). The physiological effects of slow breathing in the healthy human. Breathe, 13(4), 298-309. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5709795/

Sgoifo, A., Carnevali, L., Pico Alfonso, M. D. L. A., & Amore, M. (2015). Autonomic dysfunction and heart rate variability in depression. Stress, 18(3), 343-352. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5709795/

Steffen, P. R., Bartlett, D., Channell, R. M., Jackman, K., Cressman, M., Bills, J., & Pescatello, M. (2021). Integrating breathing techniques into psychotherapy to improve HRV: Which approach is best?. Frontiers in Psychology, 12, 624254. https://www.frontiersin.org/articles/10.3389/fpsyg.2021.624254/full