When Should I Stop Drinking Coffee?
Answer first: 8-10 hours before bed for most people, so around 1-3pm for an 11pm bedtime. Calculate your personal cutoff.
Use When Should I Stop Drinking Coffee? ↓Caffeine Half-Life Calculator
Caffeine has a half-life of about 5-6 hours. See when it will clear your system enough for quality sleep.
Caffeine in Your System
The Short Answer
Stop caffeine 8–10 hours before bed. For an 11pm bedtime that means a last coffee between 1pm and 3pm. Caffeine's half-life is five to six hours, so a 2pm flat white is still roughly a quarter-strength at midnight — enough to measurably cut deep sleep even in people who fall asleep fine.
You Don't Feel Caffeine Stealing Your Sleep
Caffeine works by blocking adenosine, the molecule that creates sleep pressure. An evening dose doesn't always stop you falling asleep; more often it quietly shallows the night, trimming deep sleep by 20–30% while you remain convinced you 'sleep fine after coffee'. The tiredness arrives the next afternoon — usually treated with more coffee.
Finding Your Personal Cutoff
Clearance speed is largely genetic (the CYP1A2 enzyme), and it slows with age, some medications and pregnancy. Run your usual drinks through the calculator above, then test moving your last dose 90 minutes earlier for one week — most people notice the difference by day four. The full science is in our caffeine half-life guide.
Frequently Asked Questions
Is 2pm too late for coffee?
For an 11pm bedtime, 2pm is around the sensible limit: with a five-hour half-life, a quarter of that caffeine is still working at midnight. If you sleep poorly or are caffeine-sensitive, move the cutoff to noon.
Why can some people drink espresso after dinner and sleep fine?
The CYP1A2 gene variant controls how fast your liver clears caffeine, and fast metabolisers can halve it in under four hours. They often still lose some deep sleep without noticing; feeling asleep is not the same as sleeping well.
Does decaf count?
Barely. Decaf typically carries 2-15mg per cup against 80-140mg for regular coffee, so an evening decaf is fine for all but the most sensitive.
Tea, cola and energy drinks too?
Yes, the cutoff applies to all caffeine. Black tea runs 40-70mg, green tea 20-45mg, cola about 35mg, energy drinks 80-160mg. The calculator lets you enter any of them.
I stopped afternoon coffee and still can't sleep - why?
Caffeine is one lever among several. Check evening light exposure, bedroom temperature and a consistent wake time next; our bedtime calculator and sleep environment score cover the rest.