Drinking coffee before a nap may seem counter intuitive.
However, many people endorse this habit as a way to boost energy levels.
This article provides a detailed look at the science behind coffee naps and whether they offer benefits.
A coffee nap refers to drinking coffee before sleeping for a short period of time.
This is thought to boost energy levels because of its effect on adenosine, a chemical that promotes sleep (1).
When you feel tired, adenosine circulates through your body in high amounts. After you fall asleep, adenosine levels begin to drop.
Caffeine competes with adenosine for receptors in your brain. So while caffeine doesn’t decrease adenosine in your body as sleep does, it prevents this substance from being received by your brain. Therefore, you feel less drowsy (1, 2, 3).
Scientists suspect that drinking coffee before a nap may boost energy levels, as sleep helps your body get rid of adenosine. In turn, caffeine has to compete with less adenosine for the receptors in your brain (1).
In other words, sleep may enhance the effects of coffee by increasing the availability of receptors for caffeine in your brain. That’s why a coffee nap may increase energy levels more than just drinking coffee or sleeping.
You may think that drinking coffee would prevent you from napping, but keep in mind that it takes some time until your body feels the effects of caffeine.
Moreover, you may fall into a type of deep sleep called slow-wave sleep if you sleep for a half-hour or more.
Waking up during slow-wave sleep can lead to sleep inertia, a state of drowsiness and disorientation. It’s thought that limiting coffee naps to less than 30 minutes may prevent this (6).
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 equivalent of four cups of coffee — six, three or zero hours before bed all experienced disrupted sleep (7).
This research indicates that it may be best to take coffee naps more than six hours before bedtime.
Finally, the amount of caffeine consumed before a coffee nap appears to impact its effectiveness.
Though the logic behind coffee naps seems plausible, research to support the claims that they increase energy more than naps or coffee alone is limited.
However, the few studies that exist are promising.
A study in 12 adults showed that participants who took 200 mg of caffeine followed by a 15-minute nap before being placed in a driving simulator for two hours felt 91% less sleepy behind the wheel than those who didn’t have caffeine and a nap (4).
A similar study in 10 people determined that those who took 150 mg of caffeine before sleeping for less than 15 minutes felt significantly less drowsy during their two hours in a driving simulator, compared to the control group (9).
Another small study showed that taking 200 mg of caffeine followed by a 20-minute nap is more effective at improving energy and performance in computer tasks than napping plus face washing or exposure to bright light (5).
While the results of these studies imply that coffee naps are effective at boosting energy, they’re small and use caffeine in pill form.
More research is needed to assess how liquid coffee before naps improves energy and alertness upon waking.
It’s not surprising that many people want to try taking coffee naps to boost energy levels or improve alertness.
However, research to support the effectiveness of coffee naps is limited.
If you’re interested in incorporating coffee naps into your day, keep in mind the type and amount of coffee you drink.
The dose of caffeine used in most studies is equivalent to approximately two cups of coffee. Consuming this amount of liquid coffee likely has the same effects as taking caffeine pills before a nap, but has not been tested.
Furthermore, drinking coffee with added sugars or flavors before sleeping may decrease the effectiveness of a coffee nap — black coffee is a healthier option.
Finally, excessive caffeine intake can cause restlessness, anxiety, muscle tremors and other issues in some people. Caffeine may also disrupt sleep if consumed less than six hours before bed (7).
Remember this recommended maximum daily caffeine intake if you increase your coffee consumption to start taking coffee naps.
Coffee naps may increase energy more than coffee or sleeping alone, though research to support this effect is limited.
About 2 cups of coffee right before a 20-minute nap may be the best way to reap benefits.
To avoid nighttime sleep disturbances, stop drinking coffee at least six hours before bed.
Coffee naps may certainly be worth a try, as long as you don’t go overboard with your caffeine consumption.