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

Close view of a wristband on an athlete's arm in daylight, showing where continuous strain tracking lives during training

Latest Cold Weather · Accuracy Cold Fingers Break Green PPG: Why Perfusion Matters More Than Sensor Count Green PPG depends on blood pulsing through skin. Cold fingers cut that pulsatile signal first, so adding LEDs can't recover what isn't there. Here's how perfusion, wavelength, and winter behavior interact. James Hoffmann Sep 17, 2026 1 min read Read article

Wearable Accuracy Has a Reporting Problem, Not Just a Sensor Problem James Hoffmann Sep 16, 2026 1 min read

Stop Trying to Raise Your Oura HRV Overnight Your Oura HRV will bounce night to night. Chasing a higher number misses the point. Here is what to watch instead for steadier sleep and recovery. James Hoffmann Sep 14, 2026 1 min read

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LATEST ARTICLES

Hand holding a matte black smart ring next to its charging case, showing the inner sensor bumps that rest against finger skin

Why Cold Fingers Break Heart Rate Tracking on Smart Rings Cold fingers don't just feel numb. Vasoconstriction shrinks the PPG signal your ring depends on, which is why winter heart rate gaps cluster on easy walks and morning commutes. James Hoffmann Sep 14, 2026 1 min read

Runner tying shoes on concrete before morning workout, showing commitment to training plan

Oura Says Rest. Your Plan Says Train. Who Wins? A low Oura Readiness Score feels like an order to rest. Here is why regular lifters and runners should treat it as one input, not the plan, and how to decide when to train anyway. James Hoffmann Sep 13, 2026 1 min read

Wearable resting on a notebook beside charts, illustrating how routine ring data looks anonymous but retains identifying patterns

De-Identified Ring Data Is Not Anonymous: What Re-Identification Studies Actually Prove Removal of your name does not make ring data anonymous. Studies show a few days of heart rate, sleep timing, and steps can single you out, and I explain what that means before you tap share. James Hoffmann Sep 13, 2026 1 min read

Bedside lamp glowing beside an unmade bed at night, showing the quiet bedroom context where alerts would interrupt sleep

Why I Told North to Stay Quiet at Night Even When Strain Spikes Nighttime heart rate spikes look urgent but rarely mean anything actionable at 2 a.m. This memo explains why I chose to keep North quiet overnight and deliver Strain context in the morning instead. James Hoffmann Sep 13, 2026 1 min read

Morning sunlight through blinds falling across an unmade bed, showing the moment a low sleep score lands

Why I Cut the Morning Score That Made People Feel Behind During Rune 1 testing I kept skipping workouts after a red morning grade. Here is why I removed that single judgment score and what we kept instead for our Q3 2026 pre-launch. James Hoffmann Sep 13, 2026 1 min read

Silver smart ring resting on a white phone, showing the small size that forces shared charging designs

Why Every Smart Ring Uses the Same Charger and What That Says About the Industry Most smart rings ship with a nearly identical pogo-pin puck. That sameness comes from shared suppliers, tight size limits, and cost pressure, and it affects repair, waste, and what you should check before you reserve. James Hoffmann Sep 13, 2026 1 min read