The Journal.
Every essay, review, field note, and interview we've published. New pieces arrive on Tuesdays; full issues close every three months.
Samsung Galaxy Unpacked 2026 and the Number Nobody Put on a Slide
0.54. That is the highest specificity any of seven consumer sleep trackers managed in Chinoy et al. (2021), published in Sleep, when 34 healthy adults slept in a lab wearing the devices while…
Twenty-One Nights With the Samsung Galaxy Watch 9: Can a Wrist Sensor See Your 4 p.m. Coffee?
The Samsung Galaxy Watch 9 lists at $349 and lands near $130 if you have a dead watch in a drawer, which is how most people will end up buying it. I bought one for a narrower reason.
Running World Records Run on Caffeine. I Gave Two Watches Six Weeks to Show Me the Bill.
Every serious conversation about running world records now includes a dosing plan. Somewhere between the carbon plate and the sodium bicarbonate sits a number in milligrams per kilogram, and it has…
An AI Fitness Coaching Comparison That Turned Into a Caffeine Audit
My evening training came with a 300 mg attachment I had stopped noticing: one scoop of pre-workout at 5:45 p.m., four nights a week, about forty-five minutes before I touched a barbell. It worked.
I Copied the Amish for Three Weeks to Fix My Circadian Rhythm — Only Half of It Worked
The advice is standard enough now that hotels print it on the notepad: no screens for an hour before bed. Dim the lamps. Buy the amber glasses.
What the Samsung Galaxy Ring Actually Knows About Your Coffee
At 7:04 this morning, my ring had an opinion. Sleep score 71, down eleven points, and beneath it a line of advice in the calm sans-serif of software that has never once been unsure of itself: consider…
I Wore Four Sleep Trackers for Ten Weeks to Find Out Which One Actually Watches My Circadian Rhythm
For ten weeks this spring I slept wearing four sleep trackers at once, because I wanted an answer to a narrow question: which of them, if any, is actually watching my circadian rhythm, and which are…
Three Flagships, One Sleeper: A Smartwatch Review of What Wearables Actually Know About Caffeine
Every flagship smartwatch review published in the last two years has carried the same implied promise: this generation, finally, the sensors are good enough. More photodiodes.
Smartwatch Review: The 41 Minutes of Deep Sleep My Watch Says Caffeine Costs Me
Forty-one minutes. That is the number this smartwatch review is built on — the gap in nightly deep sleep the Samsung Galaxy Watch Ultra 2 reported between the fifteen nights I drank coffee whenever I…
The 50 Percent Rule: How One Line About CPAP Became Veterans Policy
Fifty percent. That is what the Department of Veterans Affairs currently pays for obstructive sleep apnea when a clinician prescribes a CPAP machine and the veteran can tie the condition to service.