Coffee Naps: How They Work and When to Skip Them

What a coffee nap is

A coffee nap combines two well-known countermeasures to sleepiness: caffeine and a short nap. You drink a coffee (or another caffeinated drink), lie down straight away, and get up after a short nap of about 15 to 20 minutes.

The idea behind it: caffeine does not act instantly. It reduces sleepiness by blocking signals in the brain that contribute to feeling tired. By the time it takes effect, you are getting up from the nap. In theory, you benefit from both the nap and the caffeine at the same time.

The driving-simulator studies

The best-known research comes from the sleep laboratory at Loughborough University in the UK. In a first study, Horne and Reyner gave ten sleepy participants a 30-minute break between two monotonous one-hour afternoon drives in a car simulator. During the break they received either a nap of under 15 minutes, 150 mg of caffeine in coffee, or a decaffeinated placebo. Both the nap and the caffeine reduced driving errors and sleepiness. Simply taking a break without either did not help. [2]

In a follow-up study, Reyner and Horne combined both. Twelve sleepy participants took 200 mg of caffeine followed by a short nap during a 30-minute break before a two-hour afternoon drive. Driving incidents fell to 9% of the placebo level with the combination, compared with 34% for caffeine alone. Even participants who only dozed without real sleep benefited. [1]

Results outside the car

A Japanese study tested the combination at the desk. Ten young adults took a 20-minute nap shortly after lunch, in different conditions. Taking 200 mg of caffeine just before the nap was the most effective combination against sleepiness and for performance, with effects lasting at least an hour. Bright light or face washing after the nap also helped, but less consistently. [3]

These studies are small and were done in labs with sleepy young adults. They show that the idea is plausible, not that it works the same way for everyone.

How to try a coffee nap

1. Choose an early-afternoon slot when you have about 30 minutes.
2. Drink a coffee fairly quickly. The studies used 150–200 mg of caffeine, roughly one to two cups of brewed coffee depending on strength.
3. Lie down or lean back straight away, and set a timer for about 15–20 minutes, including some settling-in time.
4. Do not worry if you only doze; light dozing still helped in the study. [1]
5. Get up when the alarm rings and give yourself a few minutes before demanding tasks.

If you are sensitive to caffeine, pregnant, or have a heart condition, check with a doctor about how much caffeine is right for you.

Watch the clock: caffeine and night sleep

Caffeine stays in the body for hours. In a study by Drake and colleagues, a large dose of 400 mg taken even six hours before bedtime noticeably reduced sleep compared with a placebo. The authors recommend avoiding substantial caffeine for at least six hours before bed. [4]

For a typical bedtime of 11 PM, that means coffee naps are best before about 4 PM, ideally earlier. If you have trouble sleeping at night, skip the coffee and keep only the nap.

Coffee naps and driving

The studies were motivated by drowsy driving, but the message is not “drink coffee, nap, keep going”. NHTSA treats coffee and a short nap as short-term measures, not a replacement for adequate sleep. If you are drowsy, stop in a safe place, and do not continue simply because a timer has finished. [5]

The Loughborough studies looked at monotonous afternoon drives of one or two hours. They do not show how long the effect lasts on a long night drive or after severe sleep loss. [1]

When to skip the coffee nap

• Late in the afternoon or evening, if you want to sleep well at night. [4]
• If you already had several coffees today.
• If caffeine makes you jittery or anxious.
• If you are exhausted after very little sleep. Then a longer rest is more useful than a stimulant.

A plain short nap, as described in our guide to nap length, is always an option.

Common questions about coffee naps

Does tea or an energy drink work too?

The studies used coffee or caffeine tablets. Other drinks contain caffeine too, but often in different amounts.

What if I cannot fall asleep after the coffee?

Rest anyway. In the study, participants who only dozed still benefited. [1]

Can I do a coffee nap every day?

Possibly, but watch your total caffeine intake and your night sleep. If you rely on it daily, it may be worth looking at why you are so tired.