Your Stress Score Is Mostly HRV in Disguise
Most brands' "stress score" never touches your skin's electrical properties at all, it's built from the same heart rate variability data already feeding your HRV number. Only a couple of brands actually run a real electrodermal sensor.
"Stress" is one of the least standardized words on a wearable's dashboard. Underneath very similar-looking numbers, brands are running two different kinds of sensor. Electrodermal activity (EDA), also called galvanic skin response, is a real, direct measurement, a tiny current passed across the skin that changes with sweat-gland activity driven by the sympathetic nervous system. Almost no consumer wearable runs this sensor. Nearly all of them instead infer stress from heart rate variability, the same signal already powering your device's HRV and recovery numbers, repackaged under a stress-sounding name. Neither approach is fake. But they're not the same thing, and the research base behind each is at a different stage.
| Device | What they call it | What it actually measures |
|---|---|---|
| Fitbit (Sense 2, Charge 5/6, Pixel Watch) | "Stress Management Score" and "EDA Scan" | A real electrodermal sensor (cEDA), continuous background tracking plus an on-demand EDA Scan app. One of the only consumer wearables that measures skin conductance directly rather than inferring stress from heart data. |
| Garmin | "Stress Score" | Derived primarily from HRV via the wrist optical sensor, not EDA. Scored 0-100: roughly 0-25 rest, 26-50 low, 51-75 medium, 76-100 high stress. |
| Samsung Galaxy Watch | Stress tracking (no single branded score name) | A combination of HRV and heart rate measurements, the same HRV-proxy approach as Garmin, not a direct electrodermal reading. |
| Whoop | No standalone "Stress" score | Strain and Recovery serve an adjacent function, both HRV-derived. Whoop doesn't brand a separate stress metric the way Fitbit and Garmin do. |
| Oura Ring | No standalone "Stress" score | Oura doesn't offer a dedicated stress metric; its closest adjacent signals (Readiness, Resilience) are also HRV-derived composites, not electrodermal. |
This is a two-track evidence picture, not one finding. That electrodermal activity reflects sympathetic nervous system arousal during acute psychological stress is rated Emerging: reviews affirm it, but one anchor study's own finding does not cleanly affirm it, and in a social stress test of 52 people the stress group's skin conductance did not differ from the control group's while cortisol and self-reported stress did (Biological Psychology, 2024). The second track is more practical: whether a specific consumer wearable's sensor, EDA-based or HRV-proxy alike, measures that signal accurately and consistently enough for the reading to mean something day to day, rated Uncertain. A validation of the Fitbit Charge 5 found only moderate agreement with research-grade equipment for both heart rate and EDA, with a pattern of overestimating EDA (Psychophysiology, 2025), a device-specific gap rather than proof the whole category does not work.
Physiological basis: Emerging · on the Research Desk Consumer device accuracy: Uncertain · on the Research DeskCorrection, 2026-10-25
This page showed the physiological basis claim as Established. The desk moved it to Emerging on 2026-09-04, and the page now shows the current rating. Its note also said Fitbit Charge 5 heart rate tracked reasonably well; the study found only moderate agreement.
Sources: "Publication recommendations for electrodermal measurements," the field's foundational methodology reference; "Validation of the Fitbit Charge 5 for the Detection of Heart Rate and Electrodermal Activity," PMC; a scoping review of PPG-enabled wearable stress detection (290 studies screened, 23 met inclusion criteria); a scoping review of wearable EDA measurement for perceived stress (74 included studies, reporting prediction accuracies from 42% to 100%, averaging 82.6%). Garmin's and Samsung's own support documentation for their HRV-based stress-scoring design. Full study-by-study evidence lives on the Research Desk linked above.