Coffee Nap Calculator
A coffee nap is a race: caffeine you drink now needs ~45 minutes to reach your brain, while a 20-minute nap ends before sleep debt does the opposite. Done right, you wake with both engines. This tells you if the window is open — and your exact wake time.
The plan
—
How it works
Caffeine plasma level peaks roughly 45 minutes after you drink it. A 15–25 minute nap ends before deep sleep, so you wake as adenosine has been cleared and caffeine is arriving — the double effect the nap-and-espresso studies keep finding. The window closes if you drank caffeine recently: with ~100 mg still circulating, the adenosine receptors stay blocked and the nap half fails.
Timing your whole day: Caffeine Timeline · Why half-lives differ