Imagine this. You are pulling an all-nighter to study for final and you are beginning to feel exhausted. You contemplate whether to take a nap of grab a cup a coffee. It turns out you might want to do both! Have you ever heard of a coffee nap? A coffee nap is the practice of drinking coffee, then immediately taking a nap for 20 minutes before the caffeine kicks in. Who thought of such a thing and why are people doing it? It turns out, some studies are showing that taking a coffee nap is more effective in keeping you awake than drinking coffee alone or taking a nap alone. Lets see if there is any reason to believe coffee naps can live up to the hype they are receiving.
To see if this theory even makes sense, I did some research on what makes us sleepy. Humans make a chemical called adenosine. Adenosine continues to build up the longer a person stays awake. Adenosine plugs in to receptors inside your brain cells that indicate to the body you should be feeling more and more tired. This produces grogginess and is supposed to help you realize you need sleep. Adenosine levels drop as soon as you get that rest. Since caffeine has a similar chemical makeup to adenosine, it fits into these adenosine receptors, which blocks adenosine from entering. Since caffeine does not make you feel groggy, you never experience adenosine’s effects. It all comes together when you combine the two activities. Now, as sleep clears the brain of adenosine, the caffeine has no other chemicals to compete with to fill these receptors.
In theory this makes sense, but what is the science that this actually works? I found a study that tested 5 different treatments on their effectiveness of curing mid afternoon sleepiness. The 5 different treatments were drinking caffeine followed by a nap, being exposed to bright light for a minute after napping, washing the face after napping, taking a nap, and not napping at all. The subjects in each group were measured by their reaction times to an online memory test before and after their naps. It was found that the group that had caffeine before their 20-minute nap had an increase in reaction time on the memory test by 9.1 milliseconds. The group that just took a nap had an increase in reaction time as well, but only by .1 milliseconds. Also, the group that did not nap had a decrease in their reaction times by 11.6 milliseconds.
There were a few things I liked about this study. First, the design seemed logical as each person went through each treatment. This would control for third confounding variables such as the slightly different ways caffeine affects each person (some people have caffeine tolerances). It sort of levels the playing field. Also, doing a before and after test was much better than doing one test after the nap since each group had a baseline of comparison.
Unfortunately, there were many more issues with this study than good parts. For one, the sample size was only ten people. This is not a large enough sample to extend any conclusions to the population. Also, the changes in reaction time were in milliseconds. It is unclear to me whether 9 milliseconds is grounds for concluding that caffeine plus sleep is any more effective to keep you awake versus just taking a nap. Finally, this experiment may suffer from the Texas sharp shooter problem. There was no need to measure bright light or face wash after napping in this experiment. Bright light, face wash, and caffeine are all so different, it leads me to believe the researcher may have just been looking for something that stands out in the data. I realize 5 is not a huge amount of treatments to be sure this is suffering from the Texas sharp shooter problem, but it is still a red flag that all of these treatments were measured in the same study.
This one experiment is not enough to convince me coffee naps definitely cause a greater reduction of sleepiness than coffee or a nap alone. I would like to propose a more focused experiment that would involve three groups. The first group would drink a 12-ounce cup of coffee plus take a 20-minute nap. The second group would drink a 12-ounce cup of coffee. The third group would take a 20-minute nap. I would want at least 30 people in each group, making for a total sample size of at least 90. Also, I would measure their brain activity before and after the treatments using a multiple sleep latency test. The amount of brain activity a person had would be an indicator of their sleepiness. This way of measuring sleepiness is probably less prone to error than a reaction time test.
So what does this all mean? Though there is no conclusive evidence that coffee naps are effective in keeping you awake, it is one of those instances where it can’t hurt to try it out. There is no immediate risk in coffee naps, and since there is a possibility it may help you stay awake, give it a try! Just be aware more research needs to be done in order to see if there is actually a causal relationship between coffee naps and wakefulness.
Here is the video that inspired me to write about this topic!
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I find this post very interesting. The combination of caffeine and a nap is something I have never heard of. I usually find naps are better than coffee, simply because sleep is more natural, and I would rather sleep than put liquid stimulant in my body. However, this method of staying seems effective, so I may give it a try.