Caffeine Cut-off Calculator
Caffeine has a half-life of around five hours, so half of your afternoon coffee is still on duty at bedtime. Find your personal last call.
How strongly does caffeine affect you?
Your caffeine cut-off: 15:00
Anything before this has time to fade. After it, caffeine starts negotiating with your sleep, and caffeine usually wins.
Check a specific drink
About 36 mg of caffeine will still be in your system at bedtime.
Borderline: sensitive sleepers will feel this one.
The maths: caffeine halves roughly every five hours. A 95 mg mug at four in the afternoon still holds about 35 mg at midnight.
Late caffeine also suppresses REM sleep, which is exactly where your most vivid dreams live.