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# Why Is My Resting Heart Rate Going Up?

Date Published

Aug 18, 2026

Time to Read

7 min

A single morning with a higher resting heart rate is usually noise rather than information. What carries meaning is a rise that holds across several days, and in the research literature that pattern is associated with short or broken sleep, training load that hasn't been absorbed yet, and immune activation from an infection or a vaccine. Direction and duration tell you more than the height of any one reading.

## Key Takeaways

- Resting heart rate moves on its own from day to day, and among 92,457 adults wearing consumer trackers, one in five had at least one week in which their resting heart rate fluctuated by 10 beats per minute or more.
- A rise that persists for several days is the pattern worth noticing, because most of the physiological drivers of resting heart rate act over days rather than minutes.
- How long an elevation takes to resolve is often more informative than how high it went, and a persistent rise you cannot explain belongs in a conversation with a clinician rather than in an app.

## How much your resting heart rate moves on its own

You're probably here because a number went up, and before treating that as a signal it helps to know how much yours moves when nothing in particular is happening.

In a retrospective cohort of 92,457 adults in the United States who wore wrist trackers for at least 35 weeks, mean daily resting heart rate was 65 beats per minute and ranged from 40 to 109 across individuals. Most people stayed relatively stable over the short term. But 20% experienced at least one week in which resting heart rate fluctuated by 10 beats per minute or more ([Quer et al., 2020](https://pubmed.ncbi.nlm.nih.gov/32023264/)).

Two things follow. Individuals sit far apart, so comparing your number with someone else's answers very little. And the scatter inside a single person is wide enough that one high morning has a lot of ordinary movement to clear before it means anything. Usually it doesn't clear it.

## Why is my RHR high?

Resting heart rate isn't a single-cause measure. It's closer to a running total of what your cardiovascular system is currently being asked to do, which is why several unrelated inputs move it in the same direction. That's what makes a rise hard to read.

Sleep is one of the more consistently observed inputs. In a within-participant comparison drawn from 1.2 million days of wearable data in 2,596 women, a 10% decrease in weekly sleep duration was accompanied by a 1.2% increase in resting heart rate, and the shift appeared regardless of where in the menstrual cycle it occurred ([Gonzalez et al., 2026](https://pubmed.ncbi.nlm.nih.gov/42185632/)). A small percentage, observed inside the same people rather than across different ones.

Training load moves it too. Just not always in the direction you'd guess. Twenty-four recreational runners completed a three-week baseline and a two-week overload period, then split into eight overreached and twelve responders based on changes in performance and subjective recovery. During the second overload week, nocturnal heart rate rose 3.2% in the overreached group and fell 2.8% in the responders ([Nuuttila et al., 2024](https://pubmed.ncbi.nlm.nih.gov/38956784/)). Same block. Opposite directions. So a rise across heavy weeks isn't a readout of the training. It tracks what the training is currently costing you.

Immune activation is one of the clearer explanations for a multi-day rise, and it can arrive before any conscious sense of being unwell. In a cohort of nearly 5,300 smartwatch users, 32 participants developed COVID-19, and 26 of them (81%) showed alterations in heart rate, daily step count or time asleep. Of the 25 cases with symptom information available, 22 were detected before or at symptom onset, four of them at least nine days earlier ([Mishra et al., 2020](https://pubmed.ncbi.nlm.nih.gov/33208926/)). Nine days, ahead of the first symptom. We looked at the mechanism behind that timing in [Your Heart Knows Before You Do](https://haloscape.health/blog/your-heart-knows-before-you-do).

## Direction and duration, not height

Given how many inputs converge on one number, the useful readings are comparative rather than absolute.

A rolling seven-day average read against a longer one shows drift, which a single morning can't. A rise visible in the rolling line has already survived the ordinary day-to-day scatter.

Then there's how long it stays up. A known immune challenge gives a clean template for that: among 69,619 wearable subscribers, resting heart rate and respiratory rate were elevated on the first night following COVID-19 vaccination and returned to baseline within four nights ([Presby and Capodilupo, 2022](https://pubmed.ncbi.nlm.nih.gov/35019761/)). Up, then back, on a schedule. If you've tracked through a vaccination or an infection, you've probably already watched that shape happen without naming it. When an elevation has an obvious cause and clears on that timescale, the return itself is the informative part. When the same rise sits there for two weeks with no candidate explanation, the duration is the finding, not the height. Your own range is what makes that judgment possible, and it's what [HaloScape's Stress Index](https://haloscape.health/stresscore) is built to hold.

One more comparison helps here: resting heart rate rarely rises alone, and whether respiratory rate, heart rate variability and sleep shifted with it narrows the field considerably.

## The rise arrives without a label

A higher resting heart rate is a description of state, not a diagnosis. Every driver above pushes the number the same way, so the movement arrives without a label attached: a short week of sleep, an unabsorbed overload block and the first hours of an infection can all present as the same few beats. Same few beats, three different stories. A rise is a prompt to look, not a result.

So the question you arrived with is answerable, but in a narrower form than you asked it. Not why it went up. Which way it's going, and for how long. Direction and duration are the parts your own data can actually hold, and both of them are made of days rather than mornings.

Which is why the one judgment worth making is about persistence. A resting heart rate that has moved up and stayed up with no explanation you can point to is worth raising with a clinician, particularly alongside symptoms. No trend line substitutes for that conversation. Everything short of it comes down to watching whether the direction holds across the next several days, or quietly gives the beats back.

## References

- 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: retrospective, longitudinal cohort study of 92,457 adults](https://pubmed.ncbi.nlm.nih.gov/32023264/). *PLoS One.* 2020;15(2):e0227709. PMID: 32023264. doi:10.1371/journal.pone.0227709 (foundational; no equivalently sized longitudinal wearable resting heart rate cohort published since)
- Gonzalez A, O'Day JJ, Johnson SC, Kim J, Jasinski SR, Holmes KE, et al. [The menstrual cycle through the lens of a wearable device: insights into physiology, sleep, and cycle variability](https://pubmed.ncbi.nlm.nih.gov/42185632/). *NPJ Digital Medicine.* 2026. Online ahead of print, May 25. PMID: 42185632. doi:10.1038/s41746-026-02799-9
- Nuuttila OP, Uusitalo A, Kokkonen VP, Weerarathna N, Kyröläinen H. [Monitoring fatigue state with heart rate-based and subjective methods during intensified training in recreational runners](https://pubmed.ncbi.nlm.nih.gov/38956784/). *European Journal of Sport Science.* 2024;24(7):857–869. PMID: 38956784. doi:10.1002/ejsc.12115
- Mishra T, Wang M, Metwally AA, Bogu GK, Brooks AW, Bahmani A, et al. [Pre-symptomatic detection of COVID-19 from smartwatch data](https://pubmed.ncbi.nlm.nih.gov/33208926/). *Nature Biomedical Engineering.* 2020;4(12):1208–1220. PMID: 33208926. doi:10.1038/s41551-020-00640-6 (foundational; the primary reference for presymptomatic wearable detection)
- Presby DM, Capodilupo ER. [Biometrics from a wearable device reveal temporary effects of COVID-19 vaccines on cardiovascular, respiratory, and sleep physiology](https://pubmed.ncbi.nlm.nih.gov/35019761/). *Journal of Applied Physiology.* 2022;132(2):448–458. PMID: 35019761. doi:10.1152/japplphysiol.00420.2021 (retained for sample size; no comparable large wearable vaccination cohort since)

Your resting heart rate only becomes readable against the days that came before it, so build the range first and let a rise be measured against something real: open Stress Index and look at where this week sits inside your own band.