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What is resting heart rate?

Resting heart rate (RHR) is the number of times your heart beats per minute when you are completely at rest. It reflects two things at once: how much blood your heart moves with each beat, and the balance of signals reaching the heart’s natural pacemaker from your autonomic nervous system. A well-conditioned heart pumps more blood per beat, so it needs fewer beats to do the same job – which is why RHR tends to fall as cardiovascular fitness improves.

Wearable devices estimate RHR optically, using photoplethysmography (PPG) to detect the pulse at the wrist or finger. Most devices calculate the value primarily during sleep or in the minutes after waking, before you get out of bed, which is the most standardized resting condition available outside a clinic. At rest, wrist-based PPG agrees closely with electrocardiography; in one validation study of 24-hour monitoring against ambulatory ECG, error stayed under roughly 6% across the full day and was smallest during quiet periods. A larger multi-device comparison across 536 nights of simultaneous ECG recording found nocturnal RHR error of roughly 2–3% for rings and straps tested, meaning RHR is one of the more trustworthy numbers a consumer device reports.

Why resting heart rate matters

Resting heart rate is one of the most consistently replicated risk markers in cardiovascular epidemiology. A meta-analysis of 46 prospective cohort studies covering more than 1.2 million people found that each 10 bpm increase in RHR was associated with a 9% higher risk of death from any cause and an 8% higher risk of cardiovascular death. People with an RHR above 80 bpm had a 45% higher all-cause mortality risk than those in the lowest category.

A larger dose–response meta-analysis pooling 87 studies found similar per-10-bpm increases in risk across coronary heart disease (7%), stroke (6%), cardiovascular disease overall (15%), heart failure (18%), and all-cause mortality (17%). Notably, the relationship with atrial fibrillation was J-shaped rather than linear, meaning very low rates were not uniformly protective for that outcome.

An important caveat: these are associations, not proof that lowering your heart rate by itself lowers your risk. RHR is partly a summary readout of other things: fitness, autonomic tone, inflammation, thyroid function, medication, body composition, and sleep. It is useful as a signal, not as a target to be gamed.

How can I better understand my resting heart rate?

The familiar 60–100 bpm “normal adult” range comes from single clinic measurements and is broader than most people assume. Clinical guidelines have moved away from treating 60 bpm as a meaningful lower boundary. The 2018 ACC/AHA/HRS bradycardia guideline notes that the historical definition of bradycardia as under 60 bpm explicitly excludes well-trained athletes, and that population studies routinely use 50 bpm instead.

At the other end, a resting rate above 100 bpm is the conventional threshold for sinus tachycardia. The syndrome of inappropriate sinus tachycardia is defined as a resting sinus rate above 100 bpm, or a 24-hour average above 90 bpm, accompanied by distressing symptoms and with secondary causes ruled out.

The single most useful finding for anyone tracking RHR on a wearable comes from a longitudinal study of 92,457 adults with nearly 33 million daily RHR readings. The mean was 65.5 bpm, but individual averages ranged from 40 to 109 bpm: nearly 70 bpm between one person’s normal and another’s. Sex, age, BMI, and sleep duration combined accounted for no more than 10% of that spread.

SiPhox grades were built by combining population reference data with clinical guideline thresholds, and they are wellness bands for a nocturnal, wearable-derived vaue.

What changes resting heart rate?

Exercise. This is the largest modifiable factor. A systematic review and meta-analysis of 191 controlled trials covering nearly 13,000 people found that every type of exercise studied lowered RHR, with endurance training and yoga producing significant reductions in both sexes. The reduction was larger in people whose starting RHR was higher, and smaller in older participants.

Sleep. In the 92,457-adult cohort, the lowest average RHR was observed in people sleeping 7–7.5 hours per night, with higher values on either side of that window.

Alcohol. A retrospective analysis of more than 5 million person-days from 20,968 wearable users found dose-dependent increases in nocturnal resting heart rate after drinking, alongside shorter sleep and less next-day activity. A controlled nine-day monitoring study found that moderate intake raised average nocturnal RHR from 63.6 to 66.6 bpm, returning toward baseline within a few days without measurably changing sleep architecture.

Illness. A rising RHR is often the earliest objective sign of infection. In a smartwatch study published in Nature Biomedical Engineering, 81% of confirmed COVID-19 cases showed alterations in heart rate, steps, or sleep, and a two-tiered alert based on elevations relative to each person’s own baseline would have flagged 63% of cases before symptom onset. A companion Nature Medicine study found that combining sensor deviations with self-reported symptoms discriminated positive from negative cases better than symptoms alone.

Other influences. Caffeine and nicotine, dehydration, heat, acute stress, altitude, illness recovery, menstrual cycle phase, and medications can all shift RHR. Detraining raises it; a period of intensive training can lower it over weeks.

Where can I learn more?

  1. Zhang D, Shen X, Qi X. Resting heart rate and all-cause and cardiovascular mortality in the general population: a meta-analysis. CMAJ. 2016;188(3):E53–E63.
  2. Aune D, Sen A, Ó’Hartaigh B, et al. Resting heart rate and the risk of cardiovascular disease, total cancer, and all-cause mortality: a systematic review and dose–response meta-analysis of prospective studies. Nutr Metab Cardiovasc Dis. 2017;27(6):504–517.
  3. Kusumoto FM, Schoenfeld MH, Barrett C, et al. 2018 ACC/AHA/HRS guideline on the evaluation and management of patients with bradycardia and cardiac conduction delay. Circulation. 2019;140(8):e382–e482.
  4. Olshansky B, Sullivan RM. Inappropriate sinus tachycardia. EP Europace. 2019;21(2):194–207.
  5. 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. PLOS ONE. 2020;15(2):e0227709.

DISCLAIMER: IF YOU ARE CONCERNED WITH ANY OF YOUR METRICS OR RESULTS, PLEASE CONSULT WITH YOUR PHYSICIAN.