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

A thermometer showing extreme summer temperatures against a hazy sky, representing how heat waves affect smart ring biometric readings

Latest Wearables Why Heat Waves Break Your Smart Ring's Biometrics: The Vasodilation Problem Nobody Mentions Smart rings measure your finger. In a heat wave, your finger is a completely different physiological environment. Here is what actually happens to your biometrics when the temperature passes 35°C. James Hoffmann Jun 24, 2026 1 min read Read article

What GLP-1 Drugs Do to Your Smart Ring's Readings James Hoffmann Jun 23, 2026 1 min read

Oura Is Tracking Your Blood Sugar Now. Your Insurance Company Will Want That Data. Oura just integrated with Dexcom Stelo for continuous glucose monitoring. Here is what happens when your sleep tracker knows your blood sugar, and why your insurance company will want that data on a server. James Hoffmann Jun 23, 2026 1 min read

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LATEST ARTICLES

A person sleeping on their side with a smart ring on their finger, illustrating how body position compresses the finger against a pillow or mattress

Why Your Smart Ring's Nighttime Data Is a Lie: The Sleep Position Problem Nobody Mentions Your smart ring's PPG sensor assumes your finger is at heart level with unrestricted blood flow. When you sleep on your side, neither of those things is true. Here is what the data actually looks like. James Hoffmann Jun 21, 2026 1 min read

A pregnant woman wearing a smart ring, with abstract biometric data lines flowing around her finger

Your Smart Ring Has No Idea You're Pregnant: How Pregnancy Breaks Every Biometric Algorithm Pregnancy raises your resting heart rate by 10 to 20 bpm, drops your HRV, raises your temperature, and changes your sleep architecture. Every wearable algorithm trained on non-pregnant baselines gets this wrong. Here is what the data actually looks like. James Hoffmann Jun 21, 2026 1 min read

Close up of tattoo ink on skin, the very layer where PPG optical sensors struggle to read blood flow

Why Tattoos Break Your Smart Ring's PPG Sensor Tattoo ink sits right where your smart ring's PPG light needs to go. The physics of why Oura, Whoop, and every other wearable struggles with inked skin, and what it means for the next generation of optical sensors. James Hoffmann Jun 19, 2026 1 min read

An assortment of prescription medication pills scattered across a surface, representing the medications that alter biometric signals measured by smart rings

The Medications That Break Your Smart Ring's Algorithms Beta-blockers suppress HRV by 30 to 50 percent. SSRIs alter sleep architecture. Antihistamines fragment deep sleep. If you take medication and your smart ring gives you bad scores, the problem might not be your body. James Hoffmann Jun 19, 2026 1 min read

A woman in a tech workspace using a laptop, representing the underrepresentation of women in the datasets that train wearable algorithms

Your Smart Ring Was Trained on Men: The Gender Data Gap in Wearable Algorithms Most wearable algorithms are trained on datasets that are 70 to 80 percent male. Heart rate thresholds, sleep stage classifiers, and stress baselines are systematically less accurate for women. Here is why, and what Pulsyn is doing about it. James Hoffmann Jun 18, 2026 1 min read

An oscilloscope display showing a clean waveform, representing the textbook PPG signal that smart rings almost never actually capture during motion

What Your Smart Ring's Heart Rate Data Looks Like After You Move: Motion Artifacts, Adaptive Filters, and the Signal You Never See Your smart ring's PPG sensor produces clean heart rate data roughly 40 percent of the time. The other 60 percent is a signal that has been through an adaptive filter, and what comes out is a reconstruction. Here is what actually happens inside the chip when you wave your hand. James Hoffmann Jun 18, 2026 1 min read