Musical rhythms and melodies can modulate heart rate and invoke a range of emotions. Music links to the innate human desire to synchronize body movements with musical beats — dancing. This natural synchronization extends to the heart, aligning heart rate with rhythm, linking our auditory and cardiovascular systems. If multiple people are listening to or singing the same music, their heartbeats can accelerate and decelerate at the same time, and their breathing can become more synchronous.

Our heartbeats are linked intrinsically with our emotions – body and mind are inextricably interlinked through two-way transmission of nerve impulses and hormones. Positive emotions lead to more variability in heart rate which is, suprisingly, a good thing. Anger produces the greatest increases in cardiovascular measures, far more than fear.

We can feel our own heartbeats - this is called interoception and is one of the eight senses. We commonly think of five senses - sight, hearing, smell, taste, touch, but there is also proprioception (awareness of the body in 3D space), vestibular (balance), and interoception (awareness of our internal functioning). I remember becoming specifically aware of my own heart rate when I went to yoga as a student at the University of Canterbury; yoga or meditation are great ways to become more aware of parts of your body and what's going on in them. I also remember becoming aware in a less good way when I started to have very noticeable irregular heartbeats in my late twenties, when I was in a stressful role administering research funding in a government organisation. They felt like a held breath. I got a referral to a cardiologist. I cycled there, through hilly Wellington streets. She checked my heart function and said everything looked fine and I should keep on cycling. The number of irregular beats I noticed immediately plummeted after I was told everything was okay.

A recent RadioNZ article on interoception suggested people should become more aware of their heartbeats, given the role heartbeats play in our emotions. In the article, Sarah Garfinkel suggested the best way to do this is through exercise, because a strongly beating heart is easier to sense. Then one can extend awareness from when it's easy to sense to times when it's harder to sense.

The downside of being able to monitor your heart rate internally, however, is the potential to worry about whether what you are feeling is 'correct'. There's a tight link between anxiety and overanalysis of internal perceptions – like my irregular heartbeats.

Sarah Garfinkel also noted we are better able to perceive our surroundings between, rather than during, heart beats. Shooters know this – they hold their breaths, or use beta blockers to slow their heart rates down. Does this mean having a slower heart rate, achieved through regular exercise, is then a good thing because we will perceive our own lives more fully?

We can change our own heart rates deliberately – as above, shooters hold their breath. Try taking your pulse and slow your breathing down, if you haven't tried this before (it's easier with a smartwatch so you don't have to take your own pulse!). I had never tried breathing faster to increase my heart rate but attempted it for this blog - it worked! (For those who read my post about enumeration, I'm trying my smartwatch again with almost all notifications switched off...still not 100% convinced...) And, of course, it's easy to increase your heart rate by exercising.

Given the relationship between music and heartbeats, we can also change our heartbeats deliberately by listening to music with others; and presumably we also synchronise our emotions given the intrinsic linkages, not just our physiology.

Given our fractious times, listening to music together must be a good thing. I wrote about this previously, in Musical Unity – now I understand more about why music can unite people and have even stronger opinions about why our government should support creative arts, rather than seeing them as a 'nice-to-have'. We need people to get along with each other and creative arts are one way of achieving unity. Do you think the orange deal maker would agree?