Common Misconceptions

HRV (heart rate variability) and your Balance score are wonderfully useful, but they're also easy to misread. When a number takes on a life of its own, you might end up blaming yourself ("it's low today, so this is a bad day") or feeling down comparing yourself to others — the opposite of what these numbers are really for.

Feelmo's guiding principle is that we don't try to guess your feelings — we gently watch over how your body settles. On this page, we untangle the common myths one by one, with sources, so you can relate to these numbers correctly and with a light heart. Each one is wrapped up in a "so here's how to read it, and relax" form, so feel free to start wherever you like.

"Higher is always better"?

HRV is generally considered better when it's higher, but higher isn't always better. Its meaning changes with context.

• In athletes, for example, a drop in HRV has been reported to sometimes reflect "good form / tapering" rather than fatigue (Plews et al., 2013).
• Conversely, there are days when the number just won't rise even though you ought to be relaxed. That's because many factors stack up: sleep quality, how active you were that day, the timing of your measurement, and more.

How to read it: Feelmo's Balance score isn't a contest of absolute values. What matters is "how far you are from your usual self (your baseline)." The balance gauge on the Home screen comes with an aura that shows your deviation from your own baseline. Rather than fixating on a single high-or-low point, watch the "way it sways" — "I'm dipping a little low today," or "I've slowly come back over the past few days."

"One day's score decides everything"?

A single day's value swings widely with sleep, physical condition, and measurement conditions. Because HRV metrics are affected by posture, breathing, time of day, caffeine, hydration, and more, you shouldn't judge your state from a single reading or a single day (Laborde et al., 2017).

Even if it drops sharply on a given day, that might just mean "today happened to be measured that way." Lack of sleep, tension, or a reading taken while your wrist was moving a lot — the reasons vary.

How to read it: Look at it as a trend, not as a single day's point. In Feelmo, you can see:

• "Today's you" on the Home balance gauge, and
• "The flow over weeks to months" in long-term trends (Feelmo Premium),

each shown separately. Points going up and down is natural. Watching it calmly, as a line, is the healthy way to relate to HRV.

"You can compare yourself to others"?

The absolute value of HRV differs greatly by age, sex, and constitution (Umetani et al., 1998). Resting heart rate measured by wearables has also been shown to vary widely from person to person (Quer et al., 2020).

So even if the person next to you has a Balance score of 70 and yours is 55, that doesn't mean "you're less settled." You're simply not on the same playing field to begin with.

How to read it: What's meaningful isn't comparison with others, but comparison with your usual self. That's why Feelmo has no rankings and no ordering against other people. Your Balance score is calculated relative to your own baseline, and beyond the number itself, it's translated into the expressions of the six companions placed beside it. "Lively," "Calm," "Normal," "Anxious," "Overloaded," "Tired" — whichever one shows up, it's a gentle, observational word for "how you are today."

"One HRV metric tells you your state"?

Even though we say "HRV" as one word, there are many ways to look at heartbeat variability. Feelmo's Balance score is not a direct display of one public metric or a simple ratio.

The score summarizes multiple HRV-derived clues, measurement quality, and movement from your own baseline. The exact composition, weighting, and conversion method are Feelmo's proprietary analysis logic and are not disclosed publicly. Low = swaying, high = settled — a gentle scale. For more on the science behind the score, see the Science page as well.

"A single frequency ratio tells you your stress"?

One frequency-domain ratio was once said to represent "the balance between the sympathetic and parasympathetic nervous systems," but it has been pointed out that this simple interpretation does not hold (Billman, 2013).

So Feelmo doesn't treat a single ratio as "stress itself." The stress level shown on Home isn't a mechanical verdict from one ratio, either; it's a guide that gently shows the state of your balance, purely as a "sign."

How to read it: Even if your stress level reads a bit high, please don't take it as "abnormal." Think of it as a small note from your body — "maybe your sympathetic side is a little dominant right now" — and if you'd like, take a breather with the breathing exercises. That comfortable kind of distance should feel just right.

"If a watch measures it, it's medical-grade"?

The inter-beat intervals derived from the photoelectric (PPG) sensor in devices like Apple Watch agree well with the electrocardiogram at rest, but their accuracy drops during body movement (Schäfer & Vagedes, 2013). Measuring at the wrist is convenient, but the value tends to wobble when your body is moving.

How to read it: That's exactly why your Balance score is easier to read from measurements taken when your wrist is steady — while you're sitting and settled, or asleep. How the Apple Watch / HealthKit integration works, and tips for measuring stably, are summarized on the Apple Watch page. Just keep a little corner of your mind aware that, convenient a tool as it is, it differs from medical-device measurement in both its purpose and its conditions for accuracy.

"Feelmo is guessing your emotions"?

Looking at your Balance score and the expressions of the six companions, you might feel that "Feelmo has read my feelings." But that's not what's happening.

What Feelmo looks at is not emotion itself, but the state of your autonomic nervous system's balance. "It seems a little unsettled right now," "you've settled down quite a bit" — these are gentle translations of your body's state, not a verdict on the "correct answer" of your feelings. The mood itself is judged automatically by Feelmo from your overnight HRV, heart rate, and sleep — you don't pick it. Whenever you like, you can add an optional memo of your own to the Heart Log. Feelmo is a companion that quietly places your body's signs alongside it.

References

1. Plews DJ, Laursen PB, Stanley J, Kilding AE, Buchheit M. Training adaptation and heart rate variability in elite endurance athletes: opening the door to effective monitoring. Sports Medicine. 2013;43(9):773–781.
2. Laborde S, Mosley E, Thayer JF. Heart Rate Variability and Cardiac Vagal Tone in Psychophysiological Research – Recommendations for Experiment Planning, Data Analysis, and Data Reporting. Frontiers in Psychology. 2017;8:213.
3. Umetani K, Singer DH, McCraty R, Atkinson M. Twenty-four hour time domain heart rate variability and heart rate: relations to age and gender over nine decades. Journal of the American College of Cardiology. 1998;31(3):593–601.
4. Quer G, Gouda P, Galarnyk M, Topol EJ, Steinhubl SR. Inter- and intraindividual variability in daily resting heart rate and its associations with age, sex, sleep, BMI, and time of year. PLoS One. 2020;15(2):e0227709.
5. Billman GE. A frequency-domain ratio does not accurately measure cardiac sympatho-vagal balance. Frontiers in Physiology. 2013;4:26.
6. Schäfer A, Vagedes J. How accurate is pulse rate variability as an estimate of heart rate variability? International Journal of Cardiology. 2013;166(1):15–29.