When to stop drinking coffee for sleep: the 5-question quiz

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You can find your personal coffee curfew with five questions and one piece of arithmetic. Caffeine has a half-life of roughly five hours, which means an 8oz cup at about 95mg (USDA) still has around 48mg working five hours later and around 24mg ten hours later. Whether that fraction wrecks your sleep depends on your bedtime, your sensitivity, and how much you drank in total. Score yourself on the quiz below, then let the caffeine curfew calculator turn your answers into an exact last-call time. If you want the research behind the cutoff itself, that lives in our when to stop drinking coffee before bed explainer; this page is the self-test version.

The five-question quiz

1. What time do you actually fall asleep? Not bedtime, sleep time. Count backward from there.

2. What was your last caffeinated drink? An 8oz cup of coffee is about 95mg and a single espresso shot is about 63mg (USDA), so a double-shot latte is roughly 126mg no matter how much milk is in it.

3. How much did you have across the whole day? Totals matter separately from timing. The FDA cites 400mg a day as an amount generally not associated with negative effects in healthy adults, but sleep complaints show up for many people well under that.

4. Do you feel afternoon coffee at night? If a 3 p.m. cup keeps you staring at the ceiling, treat yourself as sensitive and push your curfew earlier. Sensitivity varies widely between people.

5. Is your sleep bad on coffee days specifically? Compare a heavy-coffee day against a light one. If the difference is obvious, your curfew is currently too late.

What is still in your system at a 10 p.m. bedtime

Computed from a ~5 hour half-life on a 95mg cup. Individual metabolism varies, which is the whole reason the quiz asks about sensitivity. This is information, not health advice.

Turning your score into a curfew

The pattern from the table: answered "sensitive" on question 4 or "yes" on question 5, keep your last cup 8 to 10 hours before sleep, which for a 10 p.m. bedtime means a noon to 2 p.m. curfew. Neither, and your totals are moderate, 6 hours out is a reasonable starting line to test for a week. The curfew calculator does this precisely for your bedtime, drink, and sensitivity, and shows the half-life math as it goes. For late-afternoon cravings, decaf beans keep the ritual without moving the curfew, and the caffeine database tells you what everything else in your day is adding.

Related reading

• When to stop drinking coffee before bed: the research
• How many shots of espresso is too many?
• The verified caffeine database

FAQ

What time should I stop drinking coffee for sleep? A common starting point is 6 hours before sleep, moving to 8 to 10 hours if afternoon coffee noticeably affects your nights. The curfew calculator personalizes it from your bedtime and sensitivity.

Does a 5 hour half-life mean caffeine is gone in 5 hours? No. Half-life means half remains: a 95mg cup leaves about 48mg after 5 hours and about 24mg after 10. It fades by halves, not all at once.

Can I stay under 400mg and still sleep badly? Yes. The FDA's 400mg figure is about overall daily intake for healthy adults, not timing. A modest total taken late can disturb sleep while a larger morning total does not.

Sources: USDA FoodData Central (brewed coffee ~95mg per 8oz, espresso ~63mg per oz); FDA guidance on caffeine (400mg/day context); half-life of roughly 5 hours per standard pharmacology references. Table values are arithmetic on those constants.