What Is a Caffeine Nap?

Medically reviewed by Daniel Combs, MDMedically reviewed by Daniel Combs, MD

Caffeine is a natural stimulant found in coffee that you are generally advised to avoid before bedtime as it can keep you awake. However, there are some who endorse the use of coffee for a so-called "caffeine nap."

According to research conducted in the 1990s, drinking a cup of coffee after a midday nap can increase concentration, performance skills, and cognition compared to taking a nap without the coffee.

Given that as many as one in three adults experience regular daytime sleepiness, might the benefits of a nap combined with the benefits of caffeine actually be a viable solution?

Background

The theory of the caffeine nap was tested in 1994 by researchers from Wright State University in Ohio. They recruited 24 healthy young males and randomly assigned half of them to a caffeine group and the other half to a placebo group.

After a normal night's rest, the subjects were given a series of baseline tests to assess their concentration levels, logical reasoning skills, and basic math skills. This was followed by a 24-hour period with no sleep.

Thereafter, the subjects were allowed two scheduled naps lasting 15 to 20 minutes, followed by either a 100-milligram dose of caffeine or an inactive placebo. (One cup of coffee contains roughly 100 milligrams of caffeine.) Then the thinking and math tests were repeated.

What the researchers found was that the group given caffeine achieved roughly the same scores as on their baseline tests, while those in the placebo group experienced a deterioration in all of their scores.

In their conclusions, the researchers stated that "the combination of a prophylactic nap and caffeine was more effective in maintaining nocturnal alertness and performance than was the nap alone."

Related: Is Caffeine Withdrawal Real?

Rationale

The concept of caffeine nap was based largely on the stimulant's known effects on a naturally occurring compound called adenosine that is involved in sleepiness.

Our desire for sleep involves a process known as sleep drive. This is a biological mechanism wherein the longer you stay awake, the sleepier you will become. Sleepiness itself is induced by the accumulation of adenosine, a byproduct of the body's primary energy source, known as adenosine triphosphate (ATP).

As your cells burn ATP throughout the day, the buildup of adenosine in the brain will gradually make you sleepier and sleepier. Sleep, at least in part, is the process of clearing away the accumulated adenosine. By morning, after a good night of rest, adenosine levels are largely depleted and will start to increase again the longer you're awake.

Takeaway

If you only get a few hours of sleep, you will wake up feeling sleepy because your body didn’t have sufficient time to clear the accumulated adenosine.

Caffeine can counteract this effect to some degree. By independently blocking the action of adenosine in the brain, caffeine can undermine its ability to induce sleepiness. This is how caffeine functions as a stimulant, increasing alertness and energy levels even when we should otherwise be sleepy.

Conflicting Research

As convincing as the science behind caffeine naps sounds, there are limitations to the research. Beyond the small size of the aforementioned study, the participants were all healthy and young; as such, we don't know if the same effects may occur in older adults.

A 2008 study conducted by the University of California, San Diego, involving 61 adults between the ages of 18 and 39, did not reach the same conclusions as those from Wright State University.

For this study, the subjects were given either 200 milligrams of caffeine or a placebo after a 60- to 90-minute daytime nap. Test were conducted before and after the naps, evaluating verbal memory, perceptual learning, and procedural motor skills.

Among the findings:

• There were no differences in verbal recall between either the caffeine or placebo groups.

• There were no differences in perceptual learning between either the caffeine or placebo groups.

• Caffeine actually impaired procedural motor skills compared to the placebo group (possibly due to the jitteriness caused by the equivalent of two cups of coffee).

There are also limitations to this study's findings. The main one is that a nap of 60 to 90 minutes is likely to place a person into a phase of sleep called slow-wave sleep.

Takeaway

People who awaken from delta sleep often feel groggy rather than refreshed. This can significantly blunt the stimulant effects of caffeine compared to people who take shorter naps.

Related: Does Caffeine Increase Blood Pressure?

Weighing the Evidence

Despite a lack of clear evidence that a caffeine nap will improve your motor, memory, performance, or learning skills, there is little doubt that an afternoon nap can be beneficial to your health, or that a little caffeine can increase your alertness or energy levels when you are flagging.

If you do decide to give a caffeine nap a try, try taking the nap after lunch, when you are feeling extra sleepy. This typically corresponds to a natural dip in the circadian rhythm (the biological mechanism that regulates the sleep-wake cycle) as well as the lethargy one feels after eating lunch (referred to as postprandial torpor or postprandial somnolence).

While a caffeine nap may not necessarily help you compared to a nap alone, it can have adverse effects if you take it too late. Caffeine is metabolized by the liver, and about half of it is eliminated in five to six hours.

If you are prone to insomnia, taking a caffeine nap late in the afternoon may leave you wide-eyed and unable to sleep at night.

Frequently Asked Questions

What is sleep deprivation?

Sleep deprivation is simply defined as not getting enough sleep. The amount of sleep needed can vary from person to person but, for most adults, it is between 7 to 8 hours of uninterrupted sleep.

Related: What Are the Physical Symptoms of Sleep Deprivation?

Which is better when you are tired: a nap or coffee?

According to a 2017 review of studies from the University of Queensland in Australia, the more sleep deprived you are, the more your circadian rhythm will "override" the effects of caffeine in order to force you back into a normal sleep pattern. What this suggests is that caffeine is far less beneficial than a good nap and improved sleep practices if you are chronically sleep-deprived.

How do you take a coffee nap?

A coffee nap is best taken between 1:00 p.m. and 3:00 p.m. when there is a natural dip in the circadian rhythm. The nap should be no longer than 15 to 20 minutes, during which you would enter stage 2 of sleep (referred to as light sleep). Upon awakening, drink no more than one cup of coffee; drinking more can leave you feeling jittery.

A Word From Verywell

A caffeine nap may be a quick fix for occasional daytime sleepiness, but an even better way to deal with the issue is to improve your sleep hygiene. This is a practice in which you create an atmosphere to promote ample routine sleep, including avoiding personal electronics, food, and stimulants like coffee before bedtime.

By getting enough sleep and keeping to a regular sleep schedule, you will be less likely to need caffeine to keep you going during the day.

Related: How to Fix Your Sleep Hygiene

Read the original article on Verywell Health.