When to stop caffeine before bed (the 9-hour rule)
Stop caffeine about 9 hours before you plan to sleep. A 2023 review of 24 studies found that a coffee-sized dose (about 107 mg) needs at least 8.8 hours to stop cutting into sleep, and a big pre-workout scoop (about 217 mg) needs 13.2 hours. For an 11 pm bedtime, that means your last coffee or caffeine pouch around 2 pm.
Here's why the cut-off is so early, a bedtime table you can screenshot, and when caffeine actually helps during the day.
Why caffeine reaches so far into the night
Caffeine's half-life in healthy adults is about five hours: five hours after a 100 mg dose, roughly 50 mg is still circulating, and after ten hours about 25 mg. It works by blocking adenosine, the chemical that builds "sleep pressure" through the day, so even the leftover amount can keep you lighter and more wakeful than you realise.
That last part matters. In a 2013 study in the Journal of Clinical Sleep Medicine, 400 mg of caffeine taken six hours before bed cut measured sleep by more than an hour, and the volunteers didn't notice the loss. Feeling "fine" after an evening coffee doesn't mean you slept fine.
What the 2023 review found
Researchers pooled 24 studies in Sleep Medicine Reviews. On average, caffeine:
- cut total sleep by about 45 minutes
- lowered sleep efficiency by about 7%
- added about 9 minutes to falling asleep and 12 minutes of waking in the night
- trimmed deep sleep by about 11 minutes
To avoid the loss of total sleep, they put the cut-off at 8.8 hours before bed for a standard coffee (107 mg in 250 ml) and 13.2 hours for a standard pre-workout serve (217.5 mg). These are averages across groups, not personal limits: some people clear caffeine faster, some much slower.
Your last-caffeine table
| If you sleep at | Last ~100 mg (a coffee or one pouch) by | Last ~200 mg (pre-workout scoop) by |
|---|---|---|
| 10:00 pm | 1:00 pm | 8:45 am |
| 11:00 pm | 2:00 pm | 9:45 am |
| 12:00 am | 3:00 pm | 10:45 am |
| 1:00 am | 4:00 pm | 11:45 am |
| 2:00 am | 5:00 pm | 12:45 pm |
Times are the review's 8.8 h and 13.2 h figures, rounded earlier, so treat them as a starting point and adjust if you still sleep badly.
Who should stop even earlier
Caffeine clears more slowly in some people, so the same cup lasts longer. That includes people who are pregnant (who should limit caffeine anyway and ask their doctor), people on certain medicines including some oral contraceptives, and people who simply notice they're sensitive. If one afternoon coffee leaves you staring at the ceiling, move your cut-off earlier rather than fighting it.
When caffeine does help during the day
- The mid-morning dip. Once you're properly awake is a good time for your first dose. The popular advice to always wait 90 minutes after waking isn't well supported by research; if you like your coffee at breakfast, that's fine.
- The early-afternoon slump. Around 1–3 pm is the classic dip, and a dose then still clears before a normal bedtime.
- Before training. Timing caffeine before a workout is its own question; see how to time caffeine before a workout.
- Exam season. A late-night study dose costs more sleep than it buys focus. Our guide on staying awake while studying covers the trade-off.
A note on dose
Smaller doses fade sooner, so a measured 100 mg is easier to time than a café coffee, which can hold anywhere from about 40 mg to well over 200 mg depending on the cup. Europe's food safety agency, EFSA, puts the safe ceiling for healthy adults at about 400 mg a day and single doses up to about 200 mg, and notes that even 100 mg close to bedtime can affect sleep in some adults.
FUEL caffeine pouches are exactly 100 mg each, from green coffee beans, with no sugar, no nicotine and no tobacco, so the table above works pouch for pouch. See the three flavours.
Quick answers
How many hours before bed should I stop caffeine?
About 9 hours for a coffee-sized dose (around 100 mg), based on a 2023 review of 24 studies. For a big pre-workout dose of around 200 mg, about 13 hours.
Is chai after 6 pm okay?
A cup of masala chai has less caffeine than most coffees, usually 30–50 mg depending on the tea and how long it boils, so it's gentler. If you sleep badly, it still counts. Our guide to caffeine in chai, coffee and energy drinks has the numbers.
Does caffeine affect deep sleep even if I fall asleep fine?
It can. The 2023 review found less deep sleep and more waking in the night, and in a 2013 study people lost over an hour of sleep without noticing.
What's caffeine's half-life?
About five hours in a healthy adult, with wide variation from person to person. Five hours after 100 mg, around half is left.
Is a caffeine pouch at night better than a coffee?
No. Caffeine is caffeine: 100 mg from a pouch keeps you up much like 100 mg from coffee. A pouch is just easier to measure. Use the same cut-off.