Coffee nap: how to do it and what the studies show

Key takeaways

• The idea: drink caffeine, nap for 15 to 20 minutes, and wake as caffeine’s effects begin.
• The evidence is a few small studies of 10 to 12 people each, run in labs or driving simulators.
• In one simulator study, 200 mg of caffeine plus a nap under 15 minutes cut driving incidents to 9% of placebo levels, against 34% for caffeine alone.
• Check your bedtime first: the afternoon caffeine in a coffee nap can still be in your body that night.
• A coffee nap is a short break, not a substitute for sleep and never a reason to keep driving while drowsy.

How a coffee nap is supposed to work

Caffeine works mainly by blocking receptors for adenosine, which is widely accepted as one of the brain’s natural sleep-regulating substances. Caffeine is absorbed quickly and almost completely, and EFSA says its stimulating effects may begin 15 to 30 minutes after you take it. In a small study of fasting young men who drank caffeine dissolved in water, blood levels peaked about 30 minutes later.

A coffee nap tries to use that gap. You drink the caffeine, nap while it is being absorbed, and wake around the time it starts to act, so the nap and the caffeine work back to back. "Nappuccino" and "caffeine nap" are nicknames for the same thing.

That timing logic is a rationale, not something the studies isolated: they compared how alert people were afterwards, not exactly why.

The coffee nap studies: Horne, Reyner and Hayashi

Three small experiments are behind most coffee nap advice. Two, by the same pair of researchers, used driving simulators; the third tested early-afternoon naps in a lab.

These results are encouraging but limited: 10 to 12 people per study, short follow-up, and lab or simulator settings. Nobody has shown that a coffee nap works for everyone or in everyday life, so treat it as an experiment worth trying rather than a proven method.

Why the post-lunch slump is prime coffee nap time

The mid-afternoon dip in alertness is a real phenomenon, rooted in human biology rather than in lunch itself. A review found the dip shows up even in people who skipped lunch or could not tell what time it was, though a high-carbohydrate lunch makes it worse. It does not affect everyone or every kind of performance.

That dip is when many people reach for a second coffee, and all three studies above tested the early afternoon. If coffee itself seems to leave you sleepy, why coffee makes you tired looks at the reasons.

How to take a coffee nap, step by step

Here is the method as the studies used it, with a bedtime check added:

• Check tonight first: enter your dose and bedtime in the calculator above. If a meaningful amount would still be in your system at bedtime, skip the caffeine and take a plain short nap.
• Pick a dose. The studies used 150 to 200 mg. For comparison, the FDA lists 113 to 247 mg in 12 fl oz of regular brewed coffee; see caffeine in espresso or brewed coffee for your drink.
• Drink it within a few minutes, so the whole dose starts being absorbed at once; an espresso or a cooled coffee is easier to finish quickly than a hot mug.
• Lie down straight away somewhere you can safely rest, and set an alarm for 15 to 20 minutes from lying down.
• Get up when the alarm goes, even if you did not fully fall asleep.

How long a coffee nap should be

The studies behind coffee naps used short naps: under 15 minutes in the driving studies and 20 minutes in the 2003 lab study. That is the range with evidence for this combination, so 15 to 20 minutes is the sensible target.

Longer naps were not tested with caffeine in these studies, so there is no evidence here on whether they work better or worse. For naps in general, without caffeine, goodsleep.today covers the basics.

Coffee nap timing and tonight’s sleep

The caffeine in a coffee nap does not vanish when you wake up. EFSA puts caffeine’s average half-life in healthy adults at about 4 hours, with a range of 2 to 8 hours. By simple halving arithmetic, a 3 p.m. coffee nap could leave a quarter to half of the dose in your body at an 11 p.m. bedtime.

A 2023 meta-analysis estimated that a standard coffee (107 mg) should be had at least 8.8 hours before bed to avoid losing sleep time, and a typical pre-workout serving (217.5 mg) at least 13.2 hours before. Those figures apply to those doses only, but they show a coffee nap’s caffeine can matter at night. The caffeine cutoff calculator gives your latest time, and the best time to drink coffee covers planning the whole day.

If your slump comes after your cutoff, a short nap without caffeine is the alternative.

Coffee naps and drowsy driving: where the evidence stops

Two of the coffee nap studies used driving simulators, which can make them sound like a plan for long drives. They are not. They involved small groups in a lab, measured performance for a limited time, and did not test real roads or how long the benefit lasts.

If you are too sleepy to drive safely, stop somewhere safe. In the 1996 study, a 30-minute break with a placebo coffee, without real caffeine or a nap, did not reduce impairment, so a quick stretch of the legs may not be enough on its own. For shift workers, a Cochrane review found caffeine may improve performance, but no trials measured whether it prevents injuries.

A coffee nap cannot replace a night’s sleep. If you need one most afternoons, it may be worth looking at your night-time sleep; goodsleep.today can help you plan it.

Who should skip the coffee nap or ask first

A coffee nap is still a caffeine dose. Skip it, or check with a professional first, if any of these apply:

• Pregnant: the NHS advises no more than 200 mg of caffeine a day in pregnancy, and a coffee nap dose can use most or all of that.
• Heart symptoms or high blood pressure: caffeine can raise heart rate and blood pressure; talk to your doctor before using higher doses.
• Prone to anxiety: in a study of light caffeine users, 450 mg raised anxiety in most people while 50 mg did not, so a smaller dose or a plain nap may suit you better.
• Taking medicines: some, such as the antidepressant fluvoxamine or the antibiotic ciprofloxacin, slow caffeine clearance a lot; ask your doctor or pharmacist.
• Children and teens: the American Academy of Pediatrics says the caffeine and other stimulants in energy drinks "have no place" in children’s and teenagers’ diets.

Common questions