A man drinks McDonald's McCafe coffee at its Harajuku-Omotesando shop
A series of experiments performed by scientists from UK and Japan suggests that coffee and naps taken together maximize the brain’s alertness much better than when taken alone.
Scientists at Loughborough University in Britain found out that tired test takers who drank a cup of coffee and immediately took a 15-minute nap had fewer errors in a driving simulator than those who only drank coffee or only took a nap.
The secret is in how the combination of caffeine and sleep affects a neuromodulator called adenosine. Adenosine promotes sleep and suppresses arousal and decreases heart rate so that we feel more relaxed or even tired when the level of adenosine is increased in our brain.
Normal activity slowly raises the level of adenosine but coffee reduces it because caffeine competes with adenosine for receptors in the brain, while sleep naturally clears it from the brain.
As research shows that it takes about 20 minutes for caffeine to start affecting the brain, taking a nap immediately after drinking coffee enhances its effect on adenosine. It is also important to take the 20-minute nap rather than taking a longer, more satisfying nap because a person usually enters the slow-wave sleep after 30 minutes, which makes one drowsier and tired after taking it.
Scientists say a person should drink coffee quickly in order to have enough time for the nap, which should last no more than 20 minutes. For those who do not fall asleep easily, scientists say even a half-asleep stage works.
The time of day that someone takes a coffee nap may also be important. One small study in 12 healthy adults found that participants who had 400 mg of caffeine — the rough equivalent of two tall-sized Americano— six, three or zero hours before bed all experienced disrupted sleep. This research indicates that it may be best to take coffee naps more than six hours before bedtime.
The amount of caffeine consumed before a coffee nap appears to impact its effectiveness as well. Most research suggests that 200 mg of caffeine — one cup of freshly brewed tall-sized Americano — is the approximate amount you need to feel more alert and energized upon waking.
Furthermore, drinking coffee with added sugars or flavors before sleeping may decrease the effectiveness of a coffee nap due to sugar’s property on increasing the heart rate — black coffee is a healthier option.
Finally, excessive caffeine intake can cause restlessness, anxiety, muscle tremors and other issues in some people.
Most health experts agree that up to 400 mg of caffeine a day is safe for most people, but it is considered to be difficult to measure due to having different styles of coffee consumed, types of beans used, whether a person is a regular smoker or not also affects caffeine tolerance level.
Therefore, it is important to remember this recommended maximum daily caffeine intake if you increase your coffee consumption to start taking coffee naps.
Words in this Article
Maximize – v. to increase to the greatest possible amount, make the greatest or fullest use of
Alertness – n. an attitude of readiness, caution
Immediately – adv. right away, at once, instantly
Neuromodulator – n. any various substances, like hormones and amino acids that influence the function of neurons. [neuro- of brain + modulate – v. to adjust, to change the circumstance]
Suppress – v. to put an end to the activities to hold down
Arousal – n. the state of excitement, waking up
Enhance – v. to improve, to make something better
Drowsy – adj. feeling of sleepiness
Disrupt – v. to disturb, stop one from doing something
Approximate – adj. nearly exact, about the same
Excessive – adj. more than needed, going beyond necessary
Comprehension Quiz
In the first experiment, how did they measure the effectiveness of Sleep after drinking a cup of coffee?
What does Adenosine do?
Why is taking a 30-minute nap is not recommended?
How much and when should we drink a cup of coffee in a day?
What happens if you drink too much coffee?
