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Health technology, privacy-first design, and the research behind what a ring can actually measure.

Close view of a hand with a silver ring typing on a black keyboard, showing everyday office strain tracked by wearables

Latest Stress · Wearables How Your Smart Ring Estimates Stress When It Can't Measure Cortisol No smart ring measures cortisol directly. This explainer breaks down how rings infer stress from HRV, resting heart rate, temperature, and motion, and why coffee, workouts, and bad sleep can look like stress. James Hoffmann Sep 12, 2026 1 min read Read article

Oura Raised Prices Again and the Math Now Favors No-Subscription Rings James Hoffmann Sep 11, 2026 1 min read

Smart Ring Battery Life Is a Sampling Rate Tradeoff Nobody Lists on the Spec Sheet A smart ring that promises 7 days does it by sampling less often. Here is how LED duty cycle, sampling rate, and sleep averaging interact, and what to check before you trust the numbers. James Hoffmann Sep 10, 2026 1 min read

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LATEST ARTICLES

Close-up of black dumbbells stacked in a gym, representing the grip load that compresses finger tissue during weightlifting

Why Weightlifting Breaks Your Smart Ring's Heart Rate Reading Your heart rate looks fine on a run but jumps, drops, or flatlines during lifting. The cause is mechanical: grip tension squeezes blood out of your finger while motion shakes the optical path. Here is what is happening and how to get cleaner data. James Hoffmann Sep 10, 2026 1 min read

Close-up of a silver ring worn on a finger, showing how sensor contact and fit affect optical heart rate readings

Why Tattoo Ink Breaks Your Smart Ring's Green Light Sensor Tattoo ink sits in the same skin layer your smart ring tries to read. Here is why dark ink absorbs green PPG light, when red and infrared do better, and what to check if your ring finger is tattooed. James Hoffmann Sep 10, 2026 1 min read

An ECG waveform diagram showing the difference between normal sinus rhythm and the chaotic irregular pattern of atrial fibrillation, illustrating what smart rings try to detect with PPG sensors

Your Smart Ring's AFib Detection Is Not Medical Grade. Here Is What It Actually Measures. Smart rings use PPG sensors to detect patterns that may suggest atrial fibrillation. But PPG-based AFib detection is not medical-grade diagnosis. Here is how it works, what the accuracy actually looks like, and why the Circular Ring 2 with real ECG is the exception. James Hoffmann Jun 26, 2026 1 min read

A doctor reviewing patient data on a tablet, illustrating the gap between consumer wearable metrics and clinical usefulness

Your Doctor Doesn't Want Your Wearable Data. Here Is What They Actually Want. The NYT just published a piece on what health data doctors actually find useful. The answer is three metrics. Your smart ring gives you forty. Here is why that gap exists and what it means for products like Pulsyn. James Hoffmann Jun 25, 2026 1 min read

A transparent glass cube on a table, representing algorithmic clarity and openness in health technology

89% of Smart Ring Studies Use Algorithms Nobody Can See: The Transparency Crisis in Wearable Health A new systematic review finds 89% of smart ring studies rely on proprietary algorithms that nobody outside the company can inspect. Here is what that means for the data on your wrist (or finger). James Hoffmann Jun 25, 2026 1 min read

An airplane window view at cruising altitude showing clouds and wing, with a smart ring on a finger in the foreground

Your Smart Ring Lies to You at 35,000 Feet: How Cabin Pressure Breaks SpO2, HRV, and Your Recovery Score Your smart ring was validated at sea level on healthy volunteers. At 35,000 feet in a pressurized cabin, the SpO2 calibration curve is wrong, your HRV is falsely depressed, and your recovery score takes a hit that has nothing to do with how recovered you actually are. Here is the physiology of flying and why your ring does not understand it. James Hoffmann Jun 24, 2026 1 min read