{ "registry": "KnowYourPrime Evidence Registry", "url": "https://knowyourprime.com/evidence", "methodology": "https://knowyourprime.com/methodology", "citation_pattern": "KnowYourPrime Evidence Registry, Finding [ID], version [version], reviewed [date]. [URL]", "license": { "name": "CC BY 4.0", "url": "https://creativecommons.org/licenses/by/4.0/", "attribution": "Credit KnowYourPrime and link to the finding URL." }, "fields": { "id": "Permanent finding ID, KYP-ER-NNNN. Never reused.", "rating": "Current rating label on the five-level scale.", "version": "Finding version; bumps when its text or rating changes.", "reviewed": "Date of the current version, ISO 8601.", "url": "Page to cite.", "json": "Full record: conclusion, scope, limitations, key results, rating rule reasons, studies by role, version history." }, "findings": [ { "id": "KYP-ER-0001", "title": "Smartwatch Blood Oxygen (SpO2) Accuracy Against Arterial Blood (SaO2)", "question": "Do consumer smartwatches and rings measure blood oxygen saturation (SpO2) closely enough to arterial blood oxygen (SaO2) to be meaningful?", "measurement": "Blood oxygen (SpO2)", "rating": "Uncertain", "version": "1.1", "reviewed": "2026-10-25", "url": "https://knowyourprime.com/evidence-wearable-blood-oxygen-accuracy", "json": "https://knowyourprime.com/evidence-wearable-blood-oxygen-accuracy.json" }, { "id": "KYP-ER-0002", "title": "Pulse Oximeter Accuracy and Skin Tone", "question": "Does skin pigmentation change how accurately a pulse oximeter, including one in a wearable, reads blood oxygen?", "measurement": "Blood oxygen (SpO2)", "rating": "Uncertain", "version": "1.0", "reviewed": "2026-10-24", "url": "https://knowyourprime.com/evidence-pulse-oximeter-skin-tone-bias", "json": "https://knowyourprime.com/evidence-pulse-oximeter-skin-tone-bias.json" }, { "id": "KYP-ER-0003", "title": "Wearable HRV Accuracy Against ECG", "question": "Do consumer watches, rings and bands measure heart rate variability (HRV) accurately compared with an ECG reference?", "measurement": "Heart rate variability (HRV)", "rating": "Uncertain", "version": "1.0", "reviewed": "2026-10-24", "url": "https://knowyourprime.com/evidence-wearable-hrv-accuracy", "json": "https://knowyourprime.com/evidence-wearable-hrv-accuracy.json" }, { "id": "KYP-ER-0004", "title": "Chest Strap HRV Accuracy Against ECG", "question": "Is a chest-strap heart rate monitor as accurate as a clinical ECG for heart rate variability at rest?", "measurement": "Heart rate variability (HRV)", "rating": "Established", "version": "1.0", "reviewed": "2026-10-24", "url": "https://knowyourprime.com/evidence-chest-strap-hrv-accuracy", "json": "https://knowyourprime.com/evidence-chest-strap-hrv-accuracy.json" }, { "id": "KYP-ER-0005", "title": "Readiness and Recovery Score Validity", "question": "Do consumer wearable readiness and recovery scores, and the overnight heart measurements behind them, measure what they claim accurately?", "measurement": "Readiness and recovery scores", "rating": "Uncertain", "version": "1.0", "reviewed": "2026-10-24", "url": "https://knowyourprime.com/evidence-readiness-recovery-score-validity", "json": "https://knowyourprime.com/evidence-readiness-recovery-score-validity.json" }, { "id": "KYP-ER-0006", "title": "Work Stress and HRV", "question": "Do people under more work stress have lower heart rate variability, and can that show up on a wearable?", "measurement": "Heart rate variability (HRV)", "rating": "Emerging", "version": "1.0", "reviewed": "2026-10-24", "url": "https://knowyourprime.com/evidence-work-stress-hrv", "json": "https://knowyourprime.com/evidence-work-stress-hrv.json" }, { "id": "KYP-ER-0007", "title": "Wearable Sleep Tracking Accuracy Against a Sleep Lab", "question": "Do consumer wearables measure sleep accurately compared with polysomnography in a sleep lab?", "measurement": "Sleep", "rating": "Uncertain", "version": "1.0", "reviewed": "2026-10-24", "url": "https://knowyourprime.com/evidence-wearable-sleep-tracking-accuracy", "json": "https://knowyourprime.com/evidence-wearable-sleep-tracking-accuracy.json" }, { "id": "KYP-ER-0008", "title": "Under-Mattress Sleep Sensor Accuracy", "question": "Does an under-mattress sleep sensor agree with polysomnography?", "measurement": "Sleep", "rating": "Uncertain", "version": "1.0", "reviewed": "2026-10-24", "url": "https://knowyourprime.com/evidence-under-mattress-sleep-sensor-accuracy", "json": "https://knowyourprime.com/evidence-under-mattress-sleep-sensor-accuracy.json" }, { "id": "KYP-ER-0009", "title": "Wearable Heart Rate Accuracy", "question": "Do wrist wearables measure heart rate accurately against a chest strap or ECG?", "measurement": "Heart rate", "rating": "Established", "version": "1.0", "reviewed": "2026-10-24", "url": "https://knowyourprime.com/evidence-wearable-heart-rate-accuracy", "json": "https://knowyourprime.com/evidence-wearable-heart-rate-accuracy.json" }, { "id": "KYP-ER-0010", "title": "Wearable Calorie and Energy Expenditure Accuracy", "question": "Are consumer wearables accurate enough to trust for calories burned?", "measurement": "Calories (energy expenditure)", "rating": "Uncertain", "version": "1.1", "reviewed": "2026-10-24", "url": "https://knowyourprime.com/evidence-wearable-calorie-accuracy", "json": "https://knowyourprime.com/evidence-wearable-calorie-accuracy.json" }, { "id": "KYP-ER-0011", "title": "Wearable VO2 Max Estimate Accuracy", "question": "Are smartwatch VO2 max estimates accurate against a laboratory treadmill or cycle test?", "measurement": "VO2 max (cardio fitness)", "rating": "Emerging", "version": "1.0", "reviewed": "2026-10-24", "url": "https://knowyourprime.com/evidence-wearable-vo2-max-accuracy", "json": "https://knowyourprime.com/evidence-wearable-vo2-max-accuracy.json" }, { "id": "KYP-ER-0012", "title": "Do Activity Trackers Make People More Active?", "question": "Does using a consumer activity tracker increase how physically active people become?", "measurement": "Physical activity", "rating": "Uncertain", "version": "1.0", "reviewed": "2026-10-24", "url": "https://knowyourprime.com/evidence-do-activity-trackers-increase-activity", "json": "https://knowyourprime.com/evidence-do-activity-trackers-increase-activity.json" }, { "id": "KYP-ER-0013", "title": "Overnight HRV Drop Before an Infection", "question": "Can a sudden drop in overnight heart rate variability signal an infection before symptoms start?", "measurement": "Heart rate variability (HRV)", "rating": "Emerging", "version": "1.0", "reviewed": "2026-10-24", "url": "https://knowyourprime.com/evidence-sudden-hrv-drop-before-illness", "json": "https://knowyourprime.com/evidence-sudden-hrv-drop-before-illness.json" }, { "id": "KYP-ER-0014", "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)", "rating": "Established", "version": "1.0", "reviewed": "2026-10-24", "url": "https://knowyourprime.com/evidence-normal-hrv-by-age", "json": "https://knowyourprime.com/evidence-normal-hrv-by-age.json" }, { "id": "KYP-ER-0015", "title": "VO2 Max by Age and Sex: US Reference Standards", "question": "What is a normal or good VO2 max for my age and sex?", "measurement": "VO2 max (cardio fitness)", "rating": "Established", "version": "1.1", "reviewed": "2026-10-24", "url": "https://knowyourprime.com/evidence-vo2-max-by-age-reference", "json": "https://knowyourprime.com/evidence-vo2-max-by-age-reference.json" }, { "id": "KYP-ER-0016", "title": "Wearable Sleep Stage Accuracy", "question": "Can a smartwatch or ring tell which sleep stage you are in, compared with a sleep lab?", "measurement": "Sleep", "rating": "Uncertain", "version": "1.0", "reviewed": "2026-10-24", "url": "https://knowyourprime.com/evidence-wearable-sleep-stage-accuracy", "json": "https://knowyourprime.com/evidence-wearable-sleep-stage-accuracy.json" }, { "id": "KYP-ER-0017", "title": "Can Blood Oxygen Monitoring Rule Out Sleep Apnea?", "question": "Can a smartwatch, ring or other blood oxygen sensor reliably rule out obstructive sleep apnea?", "measurement": "Blood oxygen (SpO2)", "rating": "Uncertain", "version": "1.0", "reviewed": "2026-10-24", "url": "https://knowyourprime.com/evidence-oximetry-sleep-apnea-screening", "json": "https://knowyourprime.com/evidence-oximetry-sleep-apnea-screening.json" }, { "id": "KYP-ER-0018", "title": "Smartwatch Blood Oxygen Accuracy at Altitude", "question": "Can a smartwatch blood oxygen reading be trusted at altitude?", "measurement": "Blood oxygen (SpO2)", "rating": "Uncertain", "version": "1.0", "reviewed": "2026-10-24", "url": "https://knowyourprime.com/evidence-smartwatch-blood-oxygen-at-altitude", "json": "https://knowyourprime.com/evidence-smartwatch-blood-oxygen-at-altitude.json" }, { "id": "KYP-ER-0019", "title": "Blood Oxygen Readings With Poor Circulation", "question": "Does poor circulation make a pulse oximeter or smartwatch blood oxygen reading unreliable?", "measurement": "Blood oxygen (SpO2)", "rating": "Uncertain", "version": "1.2", "reviewed": "2026-10-24", "url": "https://knowyourprime.com/evidence-blood-oxygen-poor-circulation", "json": "https://knowyourprime.com/evidence-blood-oxygen-poor-circulation.json" }, { "id": "KYP-ER-0020", "title": "Accuracy of Smartwatches With a Built-In Blood Pressure Cuff", "question": "Are smartwatches with a small inflatable cuff in the strap, such as the Huawei Watch D and D2 or Omron HeartGuide, accurate for blood pressure?", "measurement": "Blood pressure", "rating": "Uncertain", "version": "1.0", "reviewed": "2026-10-24", "url": "https://knowyourprime.com/evidence-smartwatch-cuff-blood-pressure-accuracy", "json": "https://knowyourprime.com/evidence-smartwatch-cuff-blood-pressure-accuracy.json" }, { "id": "KYP-ER-0021", "title": "Cuffless Blood Pressure Accuracy at Night", "question": "Can a cuffless smartwatch, bracelet or ring measure blood pressure accurately while you sleep?", "measurement": "Blood pressure", "rating": "Uncertain", "version": "1.0", "reviewed": "2026-10-24", "url": "https://knowyourprime.com/evidence-cuffless-blood-pressure-at-night", "json": "https://knowyourprime.com/evidence-cuffless-blood-pressure-at-night.json" }, { "id": "KYP-ER-0022", "title": "Do Calibrated Cuffless Blood Pressure Readings Track Real Changes?", "question": "After calibration with a cuff, does a smartwatch or bracelet blood pressure reading follow real changes in blood pressure?", "measurement": "Blood pressure", "rating": "Uncertain", "version": "1.0", "reviewed": "2026-10-24", "url": "https://knowyourprime.com/evidence-calibrated-cuffless-blood-pressure-tracking", "json": "https://knowyourprime.com/evidence-calibrated-cuffless-blood-pressure-tracking.json" }, { "id": "KYP-ER-0023", "title": "Apple Watch Blood Oxygen Accuracy Against Medical Devices", "question": "How accurate is the Apple Watch blood oxygen sensor compared with medical devices, including arterial blood and clinical pulse oximeters?", "measurement": "Blood oxygen (SpO2)", "rating": "Uncertain", "version": "1.2", "reviewed": "2026-10-27", "url": "https://knowyourprime.com/evidence-apple-watch-blood-oxygen-accuracy", "json": "https://knowyourprime.com/evidence-apple-watch-blood-oxygen-accuracy.json" }, { "id": "KYP-ER-0024", "title": "Oura Ring HRV Accuracy Against ECG", "question": "Is the Oura Ring's heart rate variability (HRV) reading accurate compared with an ECG?", "measurement": "Heart rate variability (HRV)", "rating": "Established", "version": "1.0", "reviewed": "2026-10-24", "url": "https://knowyourprime.com/evidence-oura-hrv-accuracy", "json": "https://knowyourprime.com/evidence-oura-hrv-accuracy.json" }, { "id": "KYP-ER-0025", "title": "Apple Watch HRV Accuracy Against ECG and Chest Straps", "question": "How accurate is Apple Watch heart rate variability (HRV) compared with an ECG or a medical-grade chest strap?", "measurement": "Heart rate variability (HRV)", "rating": "Uncertain", "version": "1.0", "reviewed": "2026-10-24", "url": "https://knowyourprime.com/evidence-apple-watch-hrv-accuracy", "json": "https://knowyourprime.com/evidence-apple-watch-hrv-accuracy.json" } ] }