Guides
Plain, sourced guides for product, research and regulatory teams building measures of recovery and change.
Boundaries
Wellness versus medical device
Where the line sits in the US and the EU, as of November 2026.
Methods
Early-warning signals explained
Critical slowing down, and what it can and cannot tell you about one person.
Data and protocols
RMSSD, lnRMSSD and windows
How to record and report HRV: transform, window and context.
IEEE 1752.1 and Open mHealth
The open schemas for sleep, activity and metadata, and how ATS-1 maps to them.
Evidence and self-report
V3 and evidence tiers
Verification, analytical and clinical validation, next to ATS-1 tiers.
WHO-5 and experience sampling
Scoring, sampling design and aligning self-report with sensors.
Questions
Who writes these guides?
ANTRL. Each guide cites its sources and shows when it was last reviewed. They are general information, not medical or legal advice.
Keep reading
Take the next step.
Plain, sourced guides for teams building wellness measures: the medical-device line, HRV and recovery, early-warning signals and ATS-1 limits.