When should you stop drinking caffeine before bed?
The research-backed cutoff is at least 6 hours before bed, and 8 to 10 if you are sensitive. Here is how to find your own caffeine curfew.
Stop caffeine at least 6 hours before bed, and 8 to 10 hours if you are sensitive or a slow metabolizer. In the most-cited study, 400 mg taken even 6 hours before bed still measurably cut sleep, and the people in it did not notice. Because caffeine has a half-life of about 5 hours, a good chunk of your afternoon cup is still working at midnight.
Why 6 hours is the floor, not a guarantee
In Drake et al. (2013), researchers gave people 400 mg of caffeine at three timings: right before bed, 3 hours before, and 6 hours before. Every single timing, including the 6-hour one, reduced measured sleep. So 6 hours is the latest defensible cutoff, not a safe-for-everyone number. If you are chasing better sleep, earlier is safer.
Your personal curfew depends on your dose and your metabolism
Two things decide how late is too late: how much caffeine you had, and how fast you clear it. A small tea clears sooner than a large cold brew. And clearance varies a lot person to person, driven mostly by the liver enzyme CYP1A2. Pregnancy, oral contraceptives, and some medications slow you down; smoking speeds you up.
| If you are... | Stop caffeine by | Why |
|---|---|---|
| An average metabolizer | ~5pm (6 hrs) | The research-backed minimum |
| Sensitive or a slow metabolizer | ~1 to 3pm | 8 to 10 hours to clear more fully |
| Drinking a large or late dose | Earlier still | More caffeine means more left at bedtime |
A simpler rule of thumb
If you do not want to do math: no caffeine after about 2pm, then see how your sleep responds over a week. Most people who move their last cup to the early afternoon notice the difference within a few nights.
Stop guessing: see exactly how much is left at bedtime
The free Caffeine and Sleep Calculator takes your drinks and your bedtime and shows how much caffeine is still in your system when your head hits the pillow, plus the latest time to have your last cup. For the full picture on how caffeine changes your night, see caffeine and sleep: how your coffee affects your night.
Sources
Written by Mike Zagare · Published
Mike Zagare is the founder of Knuckle. He tapered off a 500 to 600mg-a-day habit and built Knuckle from that protocol.
Common questions
How many hours before bed should I stop caffeine?
At least 6, which is what research supports. If you are sensitive or clear caffeine slowly, aim for 8 to 10.
Is coffee at 3pm too late?
For many people, yes. At a 5-hour half-life, a 3pm coffee still has roughly a third of its caffeine in you at an 11pm bedtime.
Does stopping earlier really help if I fall asleep fine?
Yes. Caffeine lowers deep sleep quality even when it does not keep you awake, so you can sleep through the night and still wake up unrested.
What if I need the afternoon cup to function?
Swap it for decaf to keep the ritual, or start a gradual taper so you need less. The Caffeine and Sleep Calculator shows the trade-off.
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