What HRV can tell about mental health

Source: Science Focus

Heart rate variability (HRV) is a measure of the degree of variation in time between heartbeats. Greater variation means we’re in a good place – resilient, in control of our emotions and ready for anything. Lower variation implies we need to prioritise self-care.

The type of breathing that increases HRV is known as resonant breathing, coherent breathing, or HRV biofeedback. “There are various rhythms in heart rate that each correspond to one of the body’s control systems,” explains Lehrer.

“And two of these are involved in HRV biofeedback. One of them is called respiratory sinus arrhythmia – a rhythm that goes along with breathing and is controlled by the vagus nerve, which is the major parasympathetic nerve.” So if you’re boosting that rhythm, “you’re essentially stimulating the vagus nerve – the system that helps to relax you.”

The other is called the baroreflex, which regulates blood pressure. “The baroreflex is controlled by the sympathetic nervous system,” says Lehrer. “But it has connections in the brain that connect to the structures that generate and control emotion.” So during resonant breathing, he says, “you’re stimulating systems that control emotion, essentially.”

Resonant breathing is about synchronising those two heart rhythms. You slow your natural breathing rate of about 15 breaths per minute (respiratory sinus arrhythmia) to about six times a minute (baroreflex).

To learn resonant breathing, you need a heart rate monitor connected to an HRV app, such as Elite HRV or Coherence Trainer, which shows increasing circles for inhaling and decreasing for exhaling and will let you know how well you’re doing in real time.

“It’s a godsend,” says Porges. “It’s a magic gift because we can access it through voluntary behaviour, and it has such profound effects on our neurophysiology.” In fact he calls it a type of “neural exercise”. Helpfully, in times of social distancing, we can do it on our own.

Slowing your breathing to any extent will have an effect, but it won’t be as profound as with resonant breathing. This is because with resonant breathing, you are stimulating the blood-pressure control reflexes and the respiratory control reflexes that help control gas exchange, says Lehrer.

As well as getting better athletic performance, exercise tolerance and oxygen control, you also get improved emotional control for people who are stressed or anxious.

Lehrer and his colleagues have shown that resonant breathing helps people who are suffering with emphysema, asthma, depression and related unexplained chronic pain. It is being used to treat PTSD in US veterans, and can even reduce cravings associated with various addictions. Lehrer usually recommends 20 minutes of resonant breathing twice a day, which he says will lead to “big changes in heart rate variability”.

Elsewhere, Dr David Shearer, professor of elite performance psychology at the University of South Wales, used more accessible versions of HRV biofeedback, involving just five minutes of practice per day, and still got results. He uses HRV biofeedback as a tool for teaching emotional awareness and control, to help overcome those moments when athletes crumble under pressure, known as choking.

“As sympathetic nervous system arousal increases under pressure, it reaches a point where it causes cognitive interference, to such an extent that it impedes performance,” he says. “This can manifest itself in many ways, but might include high levels of anxiety, hyper-vigilance, poor decision making, and a lack of emotional awareness. Breathing at resonant frequency is a bit like hitting the reset button.”

He says that this effect can be replicated in everyday life. Who hasn’t found themselves suddenly tongue-tied in an important meeting?

It’s a skill that takes practice to master, though, and doing the breathing doesn’t mean we should let other healthy choices slip. “The best training strategy treats the whole person,” says Dr Fredric Shaffer, president-elect of the Association for Applied Psychophysiology and Biofeedback. “HRV biofeedback is only one piece of the puzzle.”

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