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Napping: Is It A Healthy Behavior?

Rose Mirzaie

April 4, 2010

 

Abstract

The human body has two natural decreases in alertness over a 24-hour period, one around midnight and one in the mid afternoon. During this time, many people take naps, or short periods of sleep, in order to compensate for sleep deprivation. Studies show that napping improves daily activity performance, alertness, and memory. The ideal napping situation includes factors such as a calm environment, mental permission to sleep, and comfortable clothing. Nevertheless, however successful an ideal nap is, some studies show that napping may lead to obesity and diabetes, thus posing the need for an evaluation of the net benefits and hazards of napping.

 

 Napping: Is It A Healthy Behavior?

Naturally, the human body has a decrease in energy and alertness between 14:00 and 16:00 (Medrick & Drummond, 2008). To deal with this mid afternoon lethargy, many people, traditionally from Eastern and Hispanic cultures, take siestas or naps. However, napping has now become more popular all across cultures in response to longer workdays, international communication in global markets, and long commutes (Caldwell, 2001). As an incentive for this trend, studies show that a nap—qualifying as any deliberate periods of sleep lasting from three minutes to three hours (Medrick & Drummond, 2008)—increases alertness and memory. Nevertheless, some studies point to napping as a risk factor for diabetes, obesity, thus establishing the need for evaluation of naps to determine whether it poses as a predominantly healthy or unhealthy behavior of humans.

Despite the subjective benefits of naps, studies show that the body absolutely needs regular nightly sleep for maintenance of a healthy body. According to doctor Tina Benedictis, humans sleep to nurture the body and mind such as promoting a healthy immune system, repairing neurons, and fostering good mood and memory (2001). Consequently, when the body becomes sleep deprived, the immune system weakens, work and other daily routines become more challenging as memory and alertness deteriorate, and mood swings become more common.  In an effort to counteract the effects of sleep deprivation, many people choose to nap, thus bringing their minds’ state of alertness closer to a well-rested brain’s. 

A great many studies support the benefits of napping for alertness. One study by Japanese researchers Masaya Takahashi, Hideki Fukuda, and Heihachiro Arito involving the comparison of the cognitive abilities of subjects who napped and those who did not nap shows that napping enhances alertness and performance. In the study, each of the subjects had the same amount of night’s sleep but some were instructed to nap for 45 minutes after lunch (Takahashi, Fukuda & Arito, 1998). Afterwards, all of the subjects were given a task such as typing a manuscript in English. In the end, the subjects with prior naps proved to complete the tasks 15 percent better than the non-nappers. This percentage increase in alertness and performance may help support advocates of the official implementation of night shift naps. Furthermore, according to a paper by scientists Gianluca Ficca, John Axelsson, Daniel J. Mollicone, Vincenzo Muto, and Michael V. Vitiello (2009), an estimated 60 percent of workers unintentionally sleep during night shifts and in 230 self-reports by train drivers and air traffic controllers, 50 percent reported nodding off during their night shifts. Ultimately, naps seem to raise alertness and performance, and even potentially lower accidents caused by the body’s biological sleep needs. 

In addition to general alertness, studies show that napping positively affects declarative and procedural memory. In an experiment by Schoen and Badia, a two-hour nap was administered to some of the subjects after learning nonsensical words and short stories. The experimental results showed superior recall for all parts of the material in the experimental group as opposed to the control (Gianluca Ficca, John Axelsson, Daniel J. Mollicone, Vincenzo Muto & Michael V. Vitiello, 2009). In another study, subjects learned a finger movement sequence and were immediately afterwards taught another interfering finger sequence. The subjects who had a post-training nap were able to reverse the interference sequence and remember the first, while those without a post nap were unable to distinguish the first sequence from the second (Gianluca Ficca, John Axelsson, Daniel J. Mollicone, Vincenzo Muto & Michael V. Vitiello, 2009).  Thus, experiments prove that napping helps consolidate learned information and helps individuals commit information to memory. In addition, it was found in the study with finger movements that a combination of rapid eye movement sleep (REM) and slow wave sleep (SWS) produced the best results and that naps where the subjects neither entered REM nor SWS showed no memory improvement (Gianluca Ficca, John Axelsson, Daniel J. Mollicone, Vincenzo Muto & Michael V. Vitiello, 2009). This significant difference in the results that different types of naps produce serves to motivate knowledge of the characteristics of the ideal nap.

The ideal nap involves many factors such as the time of day, environment, state of mind, duration, and avoidance of caffeine. According to sleep experts, ideally one should nap between 14:00 and 16:00—the time of day with the highest sleep propensity (Medrick & Drummond, 2008). The Multiple Sleep Latency Test (MSLT)—a test measuring the time it takes to fall asleep--confirms this by showing that even individuals instructed not to nap instinctively doze off anyhow because of the natural dip in the sleep cycle during the mid afternoon (Medrick & Drummond, 2008). According to the author of Permission to Nap, the setting of a nap should be comfortable and quiet (Long, 2001) and ideally, one should be in relaxed clothing. A crucial detail of a successful nap is the subject’s mindset (Caldwell, 2001). Guilty feelings over sleeping leads to an ineffective nap and alarm clocks should be kept out of sight so as to remove the pressure of time. Lastly, sleep experts recommend naps no longer than one and a half hours to leave future night sleep undisturbed and no shorter than 10 minutes so as to reach REM sleep (Medrick & Drummond, 2008). Although these guidelines lead to successful naps in terms of alertness and performance, napping may still lead to negative outcomes such as diabetes and obesity.

Diabetes and obesity are linked. As one becomes more overweight, the risk of diabetes rises. This correlation may relate to napping since sleep decreases metabolism. Thus, a person who sleeps twice a day—once in the nighttime and once during a day-nap—experiences two periods of slower metabolism, therefore increasing the chances of obesity and consequently diabetes.  In addition to metabolism, biological mechanisms such as sleep altered hormones and neuro-endocrine control of appetite may induce insulin resistance, which leads to obesity and later diabetes (Van Cauter & Knutson, 2008). Nevertheless, socioeconomic factors may promote obesity independently of a person’s sleep habits such that a correlation between napping and diabetes becomes difficult to make. Currently, studies about diabetes and napping including socioeconomic factors and eating behaviors related to them, are lacking. However, it could easily be experimented by comparing subjects of higher class, who tend to eat more nutritious foods, to subjects of lower class, who may eat foods such as white bread and McDonalds, to see if both groups have the same incidence of diabetes.

Studies show that napping—deliberate periods of sleep lasting from three minutes to three hours (Medrick & Drummond, 2008)—increases alertness and memory. At the same time, limited research and evidence exists about the possible effects of napping on the development of obesity and consequently diabetes. Furthermore, after qualifying data on napping, one can group napping into health beneficial behaviors despite the small chance of obesity from less than two hours of slowed metabolism. For sleep-deprived individuals such as stressed college students or night shift workers, napping presents a healthy solution to maintain a full functioning brain and body. Nevertheless, to prevent dependence on napping for a decent amount of daily sleep, individuals should maximize the quality of their night sleep by avoiding caffeine and food close to bedtime, sleeping in a calm environment primarily used for sleeping, and exercising.  This, along with short, effective naps, may be the recipe for maximizing personal performance in one’s daily life.

  

References

Benedictis, Tina. (2001). Understanding sleep. Helpguide, Retrieved from

http://www.helpguide.org/life/sleeping.htm #authors

Caldwell,JA. (2001). The Impact of fatigue in air medical and other types of operations: a

review of atigue facts and potential countermeasures. Air Medical Journal, 20(1), 25-32.

Ficca, Axelsson, J.,Mollicone,DJ., Muto, V./ & Vitiello, MV. (2009). Naps, cognition

and performance. Sleep Medicine.

Long, JM. (2002). Permission to nap: taking time to restore your spirit. Retrived from

http://books.google.com/books?id=lQIJgqO0LSsC&printsec=frontcover#v=onepage&q=&f=false

Medrick, SC., & Drummond, SPA. (2008). Napping. Encyclopedia of Neuroscience, 1-6.

Van Cauter, E., & Knutson, KL. (2008). Sleep and the epidemic of obesity in children

and adults. 5-6.

Takahashi, M., Fukuda, H., & Arito, H. (1998). Brief naps during post-lunch rest: effects

on alertness, performance, and autonomic balance. European Journal of Applied Physiology and Occupational Physiology, 78 (2), 93-98

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