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.
What Google Health AI Failures Look Like After 21 Nights of Logged Caffeine
On the morning of 14 July the app told me I'd slept badly because of "caffeine later in the day." My last coffee the previous day was at 09:14.
The Google Pixel 11 Launch Put a Light Back on the Phone. I Slept Next to It for Sixteen Nights.
Google spent roughly four minutes of the Google Pixel 11 launch on a ring of twenty-four micro-LEDs under the rear glass of the Pro models and called it HiLight.
“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