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.
Fitbit Wearables Can Finally Write to Apple Health. Your Deep Sleep Number Is Still an Estimate.
The number was 38 minutes. That is what my wrist reported for deep sleep on a Tuesday in March, down from 1 hour 47 minutes the night before, on two nights that were otherwise indistinguishable except…
Patagonia, Caffeine, and the Half-Degree Problem: What Outdoor Clothing Actually Does to Your Sleep
Two nights, same patch of grass in Eryri, last July. Same tent, same bag, same tired body. On the first I lay awake for the better part of an hour doing the arithmetic you do at one in the morning.
“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