{
  "registry": "KnowYourPrime Evidence Registry",
  "license": {
    "name": "CC BY 4.0",
    "url": "https://creativecommons.org/licenses/by/4.0/",
    "attribution": "Credit KnowYourPrime and link to the finding URL."
  },
  "fields": {
    "devices": "Devices this finding names, including models it says it does not cover. What was actually tested is in scope.applies_to; exclusions are in scope.does_not_cover.",
    "evidence": "Studies by role: anchor (the rating rests on it), conflicting, null_result, supporting.",
    "industry_ties": "Device-maker ties listed in Europe PMC metadata: author_affiliations names makers an author lists as an affiliation, funders names makers listed as funding. stated_ties holds ties a paper states only in its own conflict, funding or acknowledgement text, each read from that statement and worded to say only what it says. Sources are Europe PMC metadata, funding printed in the abstract, and those reviewed statements. An empty list means no tie was found there, not that the study is independent: many papers have no open full text to read. Metadata, not a judgment of the study. checked false means no Europe PMC metadata was available."
  },
  "id": "KYP-ER-0014",
  "version": "1.0",
  "reviewed": "2026-10-24",
  "url": "https://knowyourprime.com/evidence-normal-hrv-by-age",
  "title": "Normal HRV Range by Age",
  "question": "Is there a normal heart rate variability range, and does it change with age?",
  "measurement": "Heart rate variability (HRV)",
  "devices": [
    "Oura",
    "WHOOP",
    "Apple Watch",
    "Garmin"
  ],
  "rating": {
    "label": "Established",
    "code": "established",
    "definition": "Strong, consistent evidence supports the claim.",
    "rule_version": "1.4",
    "rule_reasons": [
      "Anchor-grade evidence affirms the core relationship.",
      "Multiple supporting studies are consistent with the core relationship.",
      "Some evidence conflicts on secondary points that do not change the core direction."
    ]
  },
  "conclusion": "Yes, it falls with age. Resting HRV declines steadily from early adulthood in large reference studies and within the same people followed for 22 years, so a normal value has to be read against age, and reference ranges exist by sex and decade. The ranges are wide, and they come from ECG recordings, not from any wearable.",
  "reasoning": [
    "Four anchor studies, including two built specifically to set reference values and one that measured the same people two decades apart, all find HRV decreasing with age. That consistent affirmation rates the claim Established.",
    "Two studies add caveats rather than contradictions: HRV differs by ethnicity, with higher resting HRV in African Americans than European Americans in one meta-analysis, and an age difference seen during sleep was not found during a brief waking rest. A systematic review of normal values found variation between people so large that a single number is not meaningful."
  ],
  "key_results": [
    {
      "text": "From 24-hour Holter recordings in 695 healthy volunteers, reference values for SDNN, RMSSD, pNN50 and frequency measures were set for men and women in 10-year bands from 20 to 60, with 5th and 95th percentiles, and HRV measures decreased consistently with age.",
      "source": "doi:10.1016/j.hrthm.2016.02.006",
      "source_url": "https://doi.org/10.1016/j.hrthm.2016.02.006",
      "source_citation": "Sammito et al., Heart Rhythm, 2018"
    },
    {
      "text": "In 2,874 non-medicated healthy adults aged 35 to 74, almost all 5-minute resting HRV indices decreased with age in percentile curves by sex and decade.",
      "source": "doi:10.1111/psyp.13052",
      "source_url": "https://doi.org/10.1111/psyp.13052",
      "source_citation": "Dantas et al., Psychophysiology, 2019"
    },
    {
      "text": "In adults recorded in 1991 to 1993 and again in 2013 to 2014 (783 and 466 people), frequency-domain power, SDNN and nonlinear indices all fell significantly within the same people over 22 years.",
      "source": "doi:10.1016/j.autneu.2025.103255",
      "source_url": "https://doi.org/10.1016/j.autneu.2025.103255",
      "source_citation": "Karhumaa et al., Autonomic Neuroscience, 2025"
    },
    {
      "text": "A systematic review of 44 studies and 21,438 healthy adults found large methodological differences between studies and inter-individual variation reaching 260,000 percent for spectral measures.",
      "source": "doi:10.1111/j.1540-8159.2010.02841.x",
      "source_url": "https://doi.org/10.1111/j.1540-8159.2010.02841.x",
      "source_citation": "Nunan et al., Pacing and Clinical Electrophysiology, 2011"
    }
  ],
  "scope": {
    "applies_to": "Resting HRV measured by ECG in healthy adults, by age and sex.",
    "does_not_cover": "The specific HRV number any wearable reports, which uses its own method and timing and is not interchangeable with these reference values; HRV in people with heart disease or on medication."
  },
  "limitations": [
    "Reference values depend on the recording length and method, so a 5-minute value and a 24-hour value are not comparable.",
    "Ranges are wide; a value outside them in one person is not by itself a finding.",
    "Ethnicity and other factors shift values and are not reflected in most reference tables."
  ],
  "evidence": {
    "anchor": [
      {
        "key": "doi:10.1016/j.autneu.2025.103255",
        "title": "Changes and prognostic significance of autonomic cardiac regulation during ageing.",
        "first_author": "Karhumaa",
        "journal": "Autonomic neuroscience : basic & clinical",
        "year": 2025,
        "url": "https://doi.org/10.1016/j.autneu.2025.103255",
        "industry_ties": {
          "checked": true,
          "author_affiliations": [],
          "funders": [],
          "stated_ties": []
        }
      },
      {
        "key": "doi:10.1111/psyp.13052",
        "title": "Reference values for short-term resting-state heart rate variability in healthy adults: Results from the Brazilian Longitudinal Study of Adult Health-ELSA-Brasil study.",
        "first_author": "Dantas",
        "journal": "Psychophysiology",
        "year": 2019,
        "url": "https://doi.org/10.1111/psyp.13052",
        "industry_ties": {
          "checked": true,
          "author_affiliations": [],
          "funders": [],
          "stated_ties": []
        }
      },
      {
        "key": "doi:10.1016/j.hrthm.2016.02.006",
        "title": "Reference values for time- and frequency-domain heart rate variability measures.",
        "first_author": "Sammito",
        "journal": "Heart rhythm",
        "year": 2018,
        "url": "https://doi.org/10.1016/j.hrthm.2016.02.006",
        "industry_ties": {
          "checked": true,
          "author_affiliations": [],
          "funders": [],
          "stated_ties": []
        }
      },
      {
        "key": "doi:10.1111/j.1540-8159.2010.02841.x",
        "title": "A quantitative systematic review of normal values for short-term heart rate variability in healthy adults.",
        "first_author": "Nunan",
        "journal": "Pacing and clinical electrophysiology : PACE",
        "year": 2011,
        "url": "https://doi.org/10.1111/j.1540-8159.2010.02841.x",
        "industry_ties": {
          "checked": true,
          "author_affiliations": [],
          "funders": [],
          "stated_ties": []
        }
      },
      {
        "key": "doi:10.1016/j.jmpt.2007.04.001",
        "title": "Effect of age and sex on heart rate variability in healthy subjects.",
        "first_author": "Zhang",
        "journal": "Journal of manipulative and physiological therapeutics",
        "year": 2007,
        "url": "https://doi.org/10.1016/j.jmpt.2007.04.001",
        "industry_ties": {
          "checked": true,
          "author_affiliations": [],
          "funders": [],
          "stated_ties": []
        }
      }
    ],
    "conflicting": [
      {
        "key": "doi:10.1111/psyp.13701",
        "title": "Age-related losses in cardiac autonomic activity during a daytime nap.",
        "first_author": "Chen",
        "journal": "Psychophysiology",
        "year": 2022,
        "url": "https://doi.org/10.1111/psyp.13701",
        "industry_ties": {
          "checked": true,
          "author_affiliations": [],
          "funders": [],
          "stated_ties": []
        }
      },
      {
        "key": "doi:10.1097/psy.0000000000000133",
        "title": "Ethnic differences in resting heart rate variability: a systematic review and meta-analysis.",
        "first_author": "Hill",
        "journal": "Psychosomatic medicine",
        "year": 2015,
        "url": "https://doi.org/10.1097/PSY.0000000000000133",
        "industry_ties": {
          "checked": true,
          "author_affiliations": [],
          "funders": [],
          "stated_ties": []
        }
      }
    ],
    "supporting": [
      {
        "key": "doi:10.1007/s10286-024-01056-x",
        "title": "Comprehensive linear and nonlinear heart rate variability normative data in children.",
        "first_author": "Kakavand",
        "journal": "Clinical autonomic research : official journal of the Clinical Autonomic Research Society",
        "year": 2025,
        "url": "https://doi.org/10.1007/s10286-024-01056-x",
        "industry_ties": {
          "checked": true,
          "author_affiliations": [],
          "funders": [],
          "stated_ties": []
        }
      },
      {
        "key": "doi:10.1007/s00392-023-02248-7",
        "title": "Heart rate variability: reference values and role for clinical profile and mortality in individuals with heart failure.",
        "first_author": "Zeid",
        "journal": "Clinical research in cardiology : official journal of the German Cardiac Society",
        "year": 2024,
        "url": "https://doi.org/10.1007/s00392-023-02248-7",
        "industry_ties": {
          "checked": true,
          "author_affiliations": [],
          "funders": [],
          "stated_ties": []
        }
      },
      {
        "key": "doi:10.1016/j.hlc.2017.04.009",
        "title": "Normative Values of Short-Term Heart Rate Variability Parameters in Koreans and Their Clinical Value for the Prediction of Mortality.",
        "first_author": "Lee",
        "journal": "Heart, lung & circulation",
        "year": 2018,
        "url": "https://doi.org/10.1016/j.hlc.2017.04.009",
        "industry_ties": {
          "checked": true,
          "author_affiliations": [],
          "funders": [],
          "stated_ties": []
        }
      }
    ]
  },
  "evidence_last_evaluated": "Oct 24, 2026",
  "rating_history": [
    {
      "date": "2026-09-29",
      "rating": "Established",
      "from": null,
      "rule_version": "1.4"
    }
  ],
  "versions": [
    {
      "version": "1.0",
      "date": "2026-10-24",
      "rating": "Established",
      "change": "First published."
    }
  ],
  "research_desk": "https://knowyourprime.com/research-desk-hrv#normal-range-age",
  "related_findings": [
    "https://knowyourprime.com/evidence-wearable-hrv-accuracy",
    "https://knowyourprime.com/evidence-sudden-hrv-drop-before-illness"
  ],
  "related_articles": [
    "https://knowyourprime.com/hrv-by-age",
    "https://knowyourprime.com/what-is-a-good-hrv"
  ],
  "methodology": "https://knowyourprime.com/methodology",
  "citation": "KnowYourPrime Evidence Registry, Finding KYP-ER-0014, version 1.0, reviewed 2026-10-24. https://knowyourprime.com/evidence-normal-hrv-by-age"
}