Can I drink coffee at night? You can, but for most people a regular cup in the evening leaves enough caffeine at bedtime to make sleep shorter or lighter: an 8 oz coffee at 6 PM still leaves about 48 mg in your system at 11 PM. Whether it's a problem for you depends on three things: the dose, how close to bed you drink it, and how fast your body clears caffeine. Decaf is the easy exception.
Free toolCaffeine Cutoff CalculatorHow much caffeine is still in you at bedtime, and your latest cup.Is it bad to drink coffee before bed?
For sleep, usually yes, because caffeine lingers much longer than the buzz. With the average 5-hour half-life this site uses, half of a coffee is still in you 5 hours later, and a quarter after 10 hours.
Falling asleep fine doesn't settle it either. In an at-home sleep study, 400 mg of caffeine taken 6 hours before bed cut total sleep by more than an hour, and people generally didn't notice the loss. That's a large dose, about four cups, but it shows caffeine can affect sleep you think was normal.
Coffee at night may also shift your body clock. In a lab study, a dose similar to a double espresso taken 3 hours before bedtime delayed the evening rise in melatonin by about 40 minutes, roughly half the effect of 3 hours of bright evening light. A later body clock makes it harder to fall asleep and wake up on time.
How much caffeine is left at bedtime?
A regular 8 oz coffee (about 95 mg) at 4 PM leaves about 36 mg at an 11 PM bedtime; at 8 PM it leaves about 63 mg. Here's how it compares across drinks, using caffeine remaining = dose x 0.5^(hours / 5).
| Coffee at | Decaf, 8 oz (about 7 mg) | Espresso, 1 shot (63 mg) | Coffee, 8 oz (95 mg) | Coffee, 16 oz (190 mg) |
|---|---|---|---|---|
| 2 PM | 2 mg | 18 mg | 27 mg | 55 mg |
| 4 PM | 3 mg | 24 mg | 36 mg | 72 mg |
| 6 PM | 4 mg | 32 mg | 48 mg | 95 mg |
| 8 PM | 5 mg | 42 mg | 63 mg | 125 mg |
| 9 PM | 5 mg | 48 mg | 72 mg | 144 mg |
This site uses 25 mg at bedtime as a sensible ceiling. It isn't an official limit, but it's a useful line. A 16 oz coffee at 6 PM leaves the same amount as a fresh 8 oz cup at bedtime.
Using a different bedtime or drink? The caffeine calculator gives you the exact number and the latest time for your own cup.
How late can I drink coffee?
On average, stop regular coffee about 9 and a half hours before bed, a single espresso about 6 hours 40 minutes before, and a 16 oz coffee about 14 and a half hours before.
| Drink | Time to drop below 25 mg | Latest for 11 PM bed |
|---|---|---|
| Black tea, 8 oz (about 47 mg) | 4 h 33 min | about 6:25 PM |
| Espresso, 1 shot (63 mg) | 6 h 40 min | about 4:20 PM |
| Coffee, 8 oz (95 mg) | 9 h 38 min | about 1:20 PM |
| Coffee, 16 oz (190 mg) | 14 h 38 min | about 8:20 AM |
| Decaf, 8 oz | already under 25 mg | any time |
For an hour-by-hour view of one cup, see how long caffeine lasts.
It depends on your sensitivity
Some people clear caffeine much faster than average, and some much slower, so the same evening coffee can be harmless for one person and a bad night for another. A major review of caffeine metabolism lists genetics, smoking, pregnancy, hormonal contraceptives, liver health and some medications as factors that change how long it lasts.
A quick self-check:
- You sleep the same with or without an afternoon coffee: you may be a faster clearer. An early-evening cup may be fine, but watch for lighter sleep.
- A coffee after lunch keeps you up: you're probably slower than average. Move your cutoff to late morning.
- You're pregnant, or on medications that interact with caffeine: ask your doctor what's right for you.
What about night shifts?
If you work nights, "night" is your morning, so count back from when you'll actually go to sleep. The same math applies. If you plan to sleep at 8:30 AM after a shift, an 8 oz coffee needs to be finished by about 10:50 PM to be under 25 mg by then.
In practice, many night workers have coffee at the start of a shift and stop by the halfway point. A coffee at 2 AM would still leave about 39 mg at 8:30 AM. The shift work sleep calculator works out a caffeine cutoff around your shift and commute. For the sleep side, see sleeping during the day after a night shift and the 12-hour shift sleep schedule.
Want coffee at night? Try decaf
Decaf is the simplest way to keep an evening coffee without the caffeine: a typical 8 oz cup has only about 2 to 15 mg. As the table shows, even a decaf at 9 PM leaves only a few milligrams at bedtime. Several cups or decaf espressos can add up, though. Read more in is decaf coffee OK before bed.
Other options: half-caf earlier in the evening, herbal tea, or warm milk.
If you already had a regular coffee too late tonight, here's what to do when you can't sleep after coffee.