SLEEP & CAFFEINE
Concerned about caffeine and sleep?
If you have trouble sleeping and wonder whether coffee plays a part, estimate what may remain at bedtime and review research-based timing guidance.
Caffeine in your coffee
Content varies by product, serving size, and brewing method. Use the label value when available.
Planned bedtime
If you drink it now
Current time: —
Device time zone used for this estimate: UTC
Choose a bedtime later than now.
YOUR ESTIMATE
Estimated caffeine remaining at bedtime
Evidence and limits
- A 2025 trial (23 participants) found no significant sleep changes at 100 mg and reported effects within 12 hours at 400 mg. Participants were young men; no significant finding at 100 mg does not prove no effect.
- A 2023 meta-analysis model estimated that coffee with about 107 mg caffeine should be consumed at least 8.8 hours before bed to avoid reducing average sleep duration. This is not a personal cutoff.
- A small pharmacokinetic study of 10 healthy adult men observed half-lives from 2.7 to 9.9 hours. The range shown is that study's observed range, not a population confidence interval. Remaining caffeine is a simple model, not a direct measure of blood concentration or sleep effects.
Studies and guidance
- Gardiner et al., Sleep (2025), dose and timing trial
- Gardiner et al., Sleep Medicine Reviews (2023), meta-analysis
- Blanchard & Sawers (1983), half-life study
- EFSA, Scientific Opinion on caffeine safety
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CAFFEINE & SLEEP GUIDE
Caffeine, coffee, and trouble sleeping
People respond to caffeine differently, so there is no single coffee cutoff that is right for everyone. This tool estimates caffeine remaining at your planned bedtime from one intake and summarizes sleep timing estimates reported in research.
How long does caffeine stay in your body?
Caffeine is metabolized over time, but its half-life varies between people. The remaining amount is a simple half-life estimate, not a direct measure of alertness or sleep effects. The displayed time below 10 mg is an illustrative marker, not the time an effect ends.
If you are having trouble sleeping
Sleep is affected by many factors besides caffeine. This estimate covers one intake only; caffeine from other drinks or foods is not added automatically. See the research notes above for the limits of the evidence. This tool does not diagnose or treat sleep problems.