Coffee you love.
Sleep you need.
Most advice treats them as enemies. We think they've just been badly introduced. JavaSleep is a slow magazine about the hours between your last sip and your first dream — with honest reviews, quiet science, and one very useful calculator.
How much caffeine
will still be awake
at your bedtime?
Caffeine doesn't clock out when you do. It has a half-life of about five hours, which means your 3 PM latte is still at half strength when you're trying to fall asleep at 11. Here's the honest math.
Adjust the inputs above to see your personal timeline.
Three things worth reading slowly.
Best Travel CPAP Machines (2026): AirMini vs. Transcend Micro vs. Z2 Auto
The best travel CPAP machine for most people is still the ResMed AirMini — if you can tolerate its waterless humidification and proprietary tubing.
A Smart Ring Product Review That Starts at the Skin: 412 Nights, Three Rings, One Millimeter of Plastic
Over three years, an Oura Ring 4 costs $564.64 — $349 for the hardware, $215.64 for thirty-six months of membership at $5.99.
What the Garmin Fenix 9 Rumors Actually Change Is Your Sleep Data
The most consequential component in the next Fenix is the screen, and it has almost nothing to do with how the screen looks. That sounds like a dodge, so let me be specific.
“The most civilized thing a person can do is enjoy a cup of coffee at ten in the morning and still sleep at ten at night.— Editor's Note, Issue №001