Mindfulness and HRV

It's not just breathing — mindfulness and meditation, those "habits for settling the mind," have also been studied in relation to HRV (heart rate variability). On this page, we explain that relationship as carefully as we can, with sources. From there, we'll also gently walk you through how Feelmo watches over this habit, and how to read what it shows you.

First, what is HRV?

HRV (Heart Rate Variability) refers to the fluctuation in the intervals between heartbeats (R-R intervals). The heart doesn't beat at a fixed rhythm like a machine; the intervals stretch and shrink slightly as you breathe in and out, and as you relax or brace yourself. The size and pattern of this fluctuation reflect the balance between your sympathetic and parasympathetic nervous systems — in other words, how balanced your autonomic nervous system is.

Feelmo reads this HRV from your Apple Watch, entirely on-device, and expresses it as your Balance score on a scale of 0–100. The Balance score is built mainly around multiple HRV-derived clues, measurement quality, and movement from your own baseline. Lower tends to mean "unsettled," higher tends to mean "settled" — but what matters is not how you compare to others, it's the difference from your own baseline.

What the research is looking at

How mindfulness meditation affects the physiological markers tied to stress has been examined in systematic reviews and meta-analyses. There are reports that mindfulness / meditation interventions may work in the direction of lowering some of the physiological markers of stress, such as heart rate, blood pressure, and cortisol (Pascoe et al., 2017). Note that what this research is looking at is mainly heart rate, which is a different measure from HRV (the "fluctuation" of the heartbeat).

In a review that focused on HRV itself, while increased HRV reactivity was reported after mindfulness practice, it was also pointed out that how HRV is measured and analyzed varies widely from study to study (Christodoulou et al., 2020). In other words, "there are hints pointing in a helpful direction, but the variation in measurement is large" is the honest summary at this point.

Figure: An impression of HRV rising gently as you keep up a regular practice. This is only a conceptual illustration, not actual measurements, and the effect varies greatly from person to person.

That said, we won't overstate it

The research points in a hopeful direction, but because the variation in how things are measured is large, it needs to be read carefully (Christodoulou et al., 2020). Please keep the following in mind from the start.

• The size of the effect differs by person and situation, and it's not something we can promise will always raise your HRV if you meditate
• It's known that practices involving slow breathing tend to raise HRV transiently (Lehrer & Gevirtz, 2014). How much of the effect of mindfulness comes from breathing is still being researched
• Day-to-day numbers also wobble with sleep, caffeine, your physical condition, the timing of measurement, and more. Rather than getting elated or discouraged over a single rise or fall, we recommend looking at it as a trend over several weeks

How Feelmo handles it

Feelmo doesn't score mindfulness or meditation itself, nor force a "right way to do it" on you. All it does is gently watch over how your autonomic nervous system is doing as you try to settle yourself. When you try meditation or a breathing session, it quietly sets the shifts in your balance beside you, held up against your usual self.

How it watches (the mechanism)

• Reading HRV on-device — It receives HRV, heart rate, and the like from Apple Watch / HealthKit on-device, and builds your Balance score (0–100) mainly around multiple HRV-derived clues. Because the wrist is sensitive to body movement, values are more stable during seated on-demand measurements or while you're asleep.
• Translating into expressions, not numbers — Rather than putting the Balance score itself front and center, it translates it into the expression of the closest of your 6 companions (Genki, Odayaka, Futsuu, Fuan, Panku, and Tsukare) and places it gently at your side. This is the language of observation, not diagnosis.
• Watching the shifts in your balance — For practices such as breathing sessions, it watches over how your balance moves across your days, held up against your usual self. How the various measures are combined into the Balance score is at the core of the proprietary Feelmo analysis logic, and the details are not made public.

How to read it

• Read it as the difference from your own baseline — If you're higher and more stable than your "usual self," you're leaning toward settled; if you're lower and swinging widely, you're leaning toward unsettled. It's a gentle guide. Please don't compare it with other people's numbers.
• Read the trend, not a single day — More than the ups and downs of any given day, it's the gentle trend over time that holds meaning. Reviewing long-term trends and "the habits that are working" is unlocked in Feelmo Premium, for those who'd like a deeper look.
• When you want to confirm "does this work for me" — When you want to know whether breathing or meditation moves your balance for you yourself — not for the population average — the habit-impact analysis, Which habits help you, is helpful. In the Kokoro Report's "This week's insight," it compares your days with a habit against your days without, individually, to carefully judge "is this working for you" (Premium).

References

1. Pascoe MC, Thompson DR, Jenkins ZM, Ski CF. Mindfulness mediates the physiological markers of stress: Systematic review and meta-analysis. Journal of Psychiatric Research. 2017;95:156–178.
2. Christodoulou G, Salami N, Black DS. The Utility of Heart Rate Variability in Mindfulness Research. Mindfulness. 2020;11(3):554–570.
3. Lehrer PM, Gevirtz R. Heart rate variability biofeedback: how and why does it work? Frontiers in Psychology. 2014;5:756.