Know how much caffeine is in your system, and when you'll be clear for sleep.
Email anton@tuomainen.org. I read every message.
Why is my number lower than the mg I drank?
Caffeine isn't absorbed instantly. Each drink ramps up over about half an hour, peaks an hour or two later, then clears at your own pace, so right after a coffee the number is still climbing. This is how caffeine actually behaves in your body.
Why does a drink show a lock?
Logging it would keep you above your sleep threshold at bedtime. Tap it once and the app tells you when you would be clear to sleep if you had it. Tap it again to log it anyway, or turn that override off in Settings under Sleep Lock.
How do I log a drink I had earlier?
Tap Custom, set the Time to when you had it (a time later than now counts as yesterday), pick the drink or enter an amount, then Add.
How do I read the chart?
The solid line is your day so far, the dashed line is the forecast, and the small chip marks the day's peak. Press the chart for a moment and drag to see your level at any time.
Can I change the model to fit me?
Yes. Tap the gear to set how fast you clear caffeine, your sleep threshold, bedtime, and your own drinks: name, amount, icon, and order. You can also pick a light or dark look, or follow your phone.
Where is my data? Can I get it out?
Everything is stored privately on your device. Export your full history as a CSV from Settings anytime. Nothing is sent anywhere.
The widget looks out of date.
Widgets are refreshed by iOS on its own schedule and update within a couple of minutes; opening or closing the app refreshes it right away.
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