This is the second in a weekly series with Synapse—BU’s undergraduate science magazine. Article written by Emma Burns.
The perfect nap is the holy grail of all college students: infinitely valuable, impossible to achieve. But what does “taking a nap” even mean? Is it the 10 minutes of shut eye you caught in lecture, or is it the two hour accidental nap you took in the library? Although everyone needs a little snooze every now and then, how many students rest effectively? Studies have shown that well-timed naps can restore alertness, enhance performance, improve mood, and reduce mistakes and accidents i. So, how does one achieve the perfect nap?
Sleep is generally broken down into five stages. The first four stages are non-REM (rapid eye movement) sleep, followed by one phase of REM ii. The first sleep stage lasts between 5-10 minutes and is considered to be the transition between sleeping and waking. Although the person sleeping can still be awakened easily, his/her mind and body are gradually slowing down. If left undisturbed, the napper in stage 1 will seamlessly enter stage 2, the “restorative stage.” In stage 2, which lasts about 20 minutes, body temperature begins to drop and brain activity continues to decrease ii.
The latter stages of sleep are meant to last for several hours in order to complete the physical changes that are occurring in the brain. Stages 3, 4 and 5 are considered the deepest levels of sleep. During stages 3 and 4, the brain creates, refines and eliminates synapses, which are the connections between neurons that encode information. This promotes learning, memory and higher cognitive function. Stage 5 is REM sleep, which shows limited physical activity but intense brain activity and is most often associated with dreams ii.
The optimal nap length has been a constantly debated topic in the medical world, but the overall consensus is that if you have hit stage 3 in a nap, you have gone too far; naps should be kept shorter than 30 minutes. In 1995, Dr. Mark Rosekind, in collaboration with NASA, claimed that the ideal length of a nap was 26 minutes long iii. His study observed the effects of naps on air traffic controllers and their ability to complete their duties afterwards. The results of this study showed that performance was increased by 34% and alertness by 51%. Beyond that, Dr. Rosekind observed that naps boosted mood and improved cooperation among the subjects iii. Similarly, in 2011, the American Academy of Sleep Medicine stated that 20-30 minute naps enhanced the athletic performance of collegiate athletes iv.
However, some experts still argue that 26 minutes is too long. Dr. Jim Horne, director of the Sleep Research Centre at Loughborough University in Leicestershire, UK, argues that naps should extend no longer than 20 minutes v. He reasons that beyond 20 minutes, one runs dangerously close to entering stage 3. Once stage 3 has begun, it becomes much more difficult to wake up, and the purpose of the sleep has shifted from restorative to maintenance. Although it seems initially contradictory, Dr. Horne also argues that the most effective naps occur in combination with caffeinev. The time delay between the intake of caffeine and the time it begins to work is approximately 15 minutes v. Thus, taking a nap of equal or lesser time will allow the body to rest but not impair the effects of the caffeine. During his study of vehicular accidents due to sleepiness, Dr. Horne found that 200mg of caffeine (approximately 12oz of coffee) accompanied by a nap of 15 minutes or less decreased accidents by 34% and increased drivers’ wakefulness by one hour v.
Although the exact length of a perfect nap has yet to be determined, the impact of the nap, despite the length, can be greatly enhanced by environment. Lighting is one of the most important factors to achieving an effective nap. It is best to find areas where the lighting is low. Harsh lighting can disrupt the circadian rhythm, or internal clock, by which the body determines day from night vi. The time of day of a nap is also crucial. A study conducted in 1989 found that naps taken during the afternoon, specifically between the hours 3 and 5, showed increased sleep efficiency and alertness when compared to naps at different times of the day. The study also noted the evening “forbidden zone” for sleep to be between 7 and 9 p.m. vii
Studies have also shown that habitual nappers find their naps to be more restorative than those who do not nap frequently vii. As they say, “practice makes perfect.” So sleep on, my fellow college students. Sleep on.
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i. “Napping | National Sleep Foundation – Information on Sleep Health and Safety.” National Sleep Foundation – Information on Sleep Health and Safety | Information on Sleep Health and Safety. Web. 26 Sept. 2011. <http://www.sleepfoundation.org/article/sleep-topics/napping>.
ii. Bear, Mark F., Barry W. Connors, and Michael A. Paradiso. Neuroscience: Exploring the Brain. Philadelphia, PA: Lippincott Williams & Wilkins, 2007. Print.
iii. Rosekind, Mark R. “Alertness Management: Strategic Naps in Operational Settings.” Journal of Sleep Research 4 (1995): 62-66. Print.
iv. “Extended Sleep Improves the Athletic Performance of Collegiate Basketball Players – American Academy of Sleep Medicine (AASM).” American Academy of Sleep Medicine Association for Sleep Clinicians and Researchers. American Academy of Sleep Medicine, 1 July 2011. Web. 26 Sept. 2011. <http://www.aasmnet.org/articles.aspx?id=2374>.
v. Horne, J. A., and L. A. Reyner. “Driver Sleepiness.” Journal of Sleep Research 4 (1995): 23-29. Print.
vi. “External Factors That Influence Sleep.” Healthy Sleep. Harvard Medical School. Web. 26 Sept. 2011. <http://healthysleep.med.harvard.edu/healthy/science/how/external-factors>.
vii. Milner, Catherine E., and Kimberly A. Cote. “Benefits of Napping in Healthy Adults: Impact of Nap Length, Time of Day, Age, and Experience with Napping.” Journal of Sleep Research 18.2 (2009): 272-81. Journal of Sleep Research. Journal of Sleep Research, June 2009. Web. 22 Sept. 2011. <http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2869.2008.00718.x/full#ss1>
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