Too sleepy to open your eyes at work on Monday? Why not try a "coffee nap"?

When you feel sleepy and need to replenish your energy quickly, what will you do? Do you choose to take a nap or drink a cup of coffee to refresh yourself? In fact, there is another way to help you refresh your mind better. That is, drink a cup of coffee first, then take a nap and take a nap.

Image source: pixabay

Scientists have confirmed that doing so is actually more effective than simply drinking coffee or taking a short nap. This way of restoring energy has a name, called coffee nap. We can call it "coffee nap."

01 Can you still fall asleep after drinking coffee?

Yes, many people know that drinking coffee makes it difficult to fall asleep, and this is because of the caffeine in the coffee. But in fact, it takes some time for caffeine to affect the human body.

After coffee enters the gastrointestinal tract, it will stay there for a while, then the caffeine is absorbed into the blood by the small intestine and spread to all parts of the body, and finally takes effect in the brain. It takes about 20 minutes from the time you take coffee to the time the caffeine starts to take effect. This time difference is a good time to take a nap.

So why are coffee naps more effective in waking us up? We first need to understand what makes us dizzy and drowsy.

There is a molecule in our brain called adenosine, which is a byproduct of brain activity and is continuously produced and accumulated throughout the day. Adenosine binds to adenosine receptors in the human brain, which not only inhibits the activity of nerve cells and makes people feel tired, but also occupies the space for dopamine - one of the functions of dopamine is to make people feel happy, so people will feel unhappy after being tired.

Caffeine and adenosine have similar chemical structures. When caffeine enters the brain, it can also bind to the receptors before adenosine, giving the brain the illusion of not being tired - because the adenosine produced by overwork still exists, but the brain cannot feel it due to the presence of caffeine. In addition, since the receptors are not affected by adenosine, dopamine can also work normally, so caffeine can also make people feel happy at the same time.

In addition, the human body can naturally clear adenosine from the brain during sleep, and caffeine does not even need to compete with adenosine to enter the receptors. Therefore, drinking coffee and then taking a nap will have a better effect.

One study asked participants to perform a one-hour simulated driving test and report how sleepy they were every three minutes. The results showed that participants who drank coffee and took a 15-minute nap were consistently more alert and made fewer mistakes in the simulated driving than those who drank coffee or took a nap alone.

Meanwhile, a Japanese study found that people who enjoyed coffee and took a nap also performed better on a series of memory tests.

02 What is the correct way to take a “coffee nap”?

Drink coffee.

The key to a coffee nap is to time it well, so it's best to drink the coffee quickly rather than savor it. To get enough caffeine, try espresso.

Set an alarm for about 20 minutes and then take a nap.

Some people may feel pressured by the deadline and have trouble falling asleep. But it doesn't matter. Studies show that even if you have trouble falling asleep, a 20-minute nap in a semi-dream state can still achieve the desired effect. But remember not to nap for more than 30 minutes. After entering deep sleep, you will feel even more groggy when you wake up.

The best time for a coffee nap is between 1pm and 3pm.

Because the half-life of caffeine (the time it takes for half of the drug concentration in the body to disappear) is 3-5 hours, drinking coffee too late may affect your sleep at night.

Although coffee + nap can be a good way to refresh your mind, it cannot achieve the same effect as adequate deep sleep. In the long run, if you want to improve your work efficiency, you still need to rely on regular work and rest and good sleep.

The article is produced by Science Popularization China-Starry Sky Project (Creation and Cultivation). Please indicate the source when reprinting.

Author: Science scraps popular science team

Reviewer: Chen Ran, Associate Research Librarian (Science Communication) / Senior Engineer, COFCO Nutrition and Health Research Institute