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Insights on health technology, privacy-first design, and the science behind smarter wearables.

LATEST ARTICLES

A data visualization dashboard showing charts and graphs. The kind of population statistics that power wearable health age scores, but which do not represent any individual accurately.

What 'Health Age' Actually Means and Why Pulsyn Doesn't Use It

Most wearables give you a health age or body age score that compares your biometrics to a population average. The math is a regression model, not a medical diagnosis. Pulsyn does not show one because the number is statistically invalid for the individual reading it.

James Hoffmann

Jun 6, 2026 13 min read

A closeup of a lithium polymer battery cell showing the internal structure and power density constraints that make smart ring battery life a physics problem

Smart RingsHardwareWearables

Why Smart Ring Battery Life Is a Physics Problem, Not a Marketing Problem

Most smart ring manufacturers advertise 7-day battery life. That number comes from a test mode where the heart rate monitor is off and the wearer is asleep. In real use, the gap between marketing and physics is about 40 percent.

James Hoffmann

Jun 5, 2026 14 min read

A digital privacy concept image showing data security and protection themes

HipaaFtcLegislation

Your Wearable Data Isn't Covered by HIPAA. The FTC, Congress, and 20 States Are Trying to Fix That.

Your fitness tracker data is not protected by HIPAA. The FTC, Congress, and 20 states are trying to fix that, but legislation only regulates what companies can do with data they already possess. Pulsyn removes the server entirely.

James Hoffmann

Jun 5, 2026 11 min read

A smartphone screen showing a minimal dark interface without login forms or password fields

PrivacyData OwnershipLocal First

How Pulsyn Works Without a Login Screen

Most health apps start with a login form because their business model requires your email before their product requires your data. Pulsyn starts with a heart rate graph because the app stores everything locally on your phone and has nothing to authenticate against.

James Hoffmann

Jun 4, 2026 11 min read

A conceptual visualization of stress physiology showing the interconnected nervous system response that wearable devices attempt to measure

StressAlgorithmHrv

What Goes Into Pulsyn's Stress Score

Most wearables compute a stress score by running your heart rate through a black box. Pulsyn does the same thing, but the weights are public, the math is in the repository, and the app tells you exactly how confident it is. Here is the full breakdown.

James Hoffmann

Jun 4, 2026 13 min read

A close-up of a heart rate monitor sensor on a finger, showing the pulse reading in real time

AlgorithmsAccuracyHeart Rate

How Pulsyn Calculates Resting Heart Rate (and Why Your Current Number Is Probably Wrong)

Most wearables report resting heart rate as the lowest heart rate they can find, usually during sleep. The clinical definition is different. Pulsyn measures it during motionless awake periods, and the gap between the two definitions is often 10 to 15 beats per minute.

James Hoffmann

Jun 3, 2026 13 min read

A runner on a track at sunset, the exact scenario where smart ring heart rate tracking fails due to finger blood flow physics

AccuracyExerciseFitness Tracking

Why Smart Rings Are Bad at Workout Tracking, and the Physics of Finger Blood Flow

Smart rings promise workout tracking, but the physics of finger blood flow makes PPG nearly useless during exercise. Here is why the heart rate data is often fabricated, and why Pulsyn does not pretend otherwise.

James Hoffmann

Jun 3, 2026 13 min read

A neon-lit circuit board representing the internal hardware of wearable devices that users are reverse engineering to reclaim their health data

OuraSubscriptionOpen Source

Why People Are Cracking Their Oura Rings

A Reddit post called Cracked Oura hit 769 upvotes by showing how to bypass Oura's mandatory subscription using raw BLE data. The thread turned into a product support forum for a product Oura refused to build.

James Hoffmann

Jun 2, 2026 14 min read

A hotel room at night with an unmade bed, representing the unfamiliar environment where the first night effect occurs and sleep trackers get confused

First Night EffectOuraScience

How Traveling Breaks Your Sleep Tracker (and Why the First Night Effect Is Real)

The first night effect is a documented neurological phenomenon where half your brain stays awake in unfamiliar environments. Most wearables treat this as a bad night and tank your score. They should be treating it as a different kind of night entirely.

James Hoffmann

Jun 1, 2026 11 min read