“MC equals MP… profit maximizing…”  Mumbling to yourself, you walk out of the Bryan Center after eating a satisfying Beef Enchilada at Armadillo Grill.  For the entire morning you panicked about your upcoming econ midterm.  You take a glance at your wristwatch and realize it is only 12:30 PM, but you’re already yawning.  What should you do with an hour and a half left before the exam?  Cram more formulas into your brain? Go through your notes one more time? Or how about getting a tall cappuccino and heading for a nap?  

It is common for people to have post-lunch sleepiness which results in a decrease in performance.  What can you do to avoid this?  Nap? Get a caffeine jolt?  A recent study suggests that the best option is to do both!  Although this sounds contradictory, the study, done by Hayashi et al. (2003) of Hiroshima University in Japan, shows that the combination of caffeine intake and a short nap most effectively counteracts post-lunch sleepiness. 

Other than drinking caffeine, the researchers tested other possible options to prevent post-lunch sleepiness.  Ten healthy university students went through five experimental conditions each lasting for about 20 minutes.  The conditions included:

·        no nap

·        nap only

·        drinking coffee (200 mg of caffeine) followed by a nap

·        nap followed by face washing

·        nap and then exposed to bright light for one minute immediately after 

To understand the effect of the caffeine and nap combination relative to other options, we need to have a look at the analyses of the experiments.

  The analyses of the research include the participants’ performance on a memory search task and their subjective ratings on sleepiness.  The memory search task is a simple test where the participants are asked to identify two specific letters from a chain of random letters for 60 minutes after the experimental condition.  Results showed that drinking coffee before the nap had the best performance.  The participants only averaged a 1% error as compared to no nap (6.7%), nap only (5.7%), face washing (3.3%), and bright light exposure (1.7%). 

On a rating from 0 (very alert) to 100 (very sleepy), the participants rated their sleepiness during the end of the memory search task.  When the participants drank coffee before taking the nap, the average sleepiness was only about 36.  In contrast, taking no naps resulted in a sleepiness rating of 91.  The rating for just taking a nap is 69, face washing is 60, and bright light exposure is 44.

Interestingly, when the participants were exposed to bright light, their results in both the memory search task and sleepiness rating was only out performed when they drank coffee before the nap.  So if you don’t like coffee, exposing to a bright light for a minute after the nap can have similar effects (CAUTION: long term exposure to bright light can damage your eyes!).

Naps are crucial to many of us and we should know how to nap effectively.  The study tells us that drinking coffee before a nap increases performance drastically as compared to only taking a nap.  You might be asking, “How can I fall asleep after drinking coffee?”  Because it normally takes about 45 minutes in order for 99% of the caffeine to be absorbed, caffeine will generally not affect falling asleep immediately after drinking coffee.  However, make sure you finish the coffee quick enough before the caffeine starts acting on your body. 

Another question you might be asking is, “But how much coffee do I have to drink?”  The study used 200 mg of caffeine which is roughly equivalent to three cups of coffee.  That is definitely too much coffee for anyone.  Since each person is different, test out different amounts of coffee and see which works the best for you. 

So next time you have a midterm coming up, drink some coffee, take a nap, and see your grades increase. 

 

References

Hayashi, M., Hori, T., Masuda, A. (2003). The alerting effects of caffeine, bright light and face washing after a short daytime nap. Clinical Neurophysiology, 113, 2268-2278.

 

 

Further Reading

 

Bowman, T. (2003). Sleep Stages. Retrieved Dec. 3, 2003, from Healthcommunications: http://www.sleepdisorderchannel.net/stages

 

Sabbatini, R. (1997). The History of the Electroencephalogram. Brain and Mind: Electronic Magazine on Neuroscience, 3. Retrieved Dec. 3 2003, from The History of the Electroencephalogram