The Science Of Naps

Studies are being conducted to determine the benefits - and possible drawbacks - of snoozing in the afternoon.

A nap is becoming a workplace trend. Feeling drowsy? You can have a cup of coffee or take a walk, but there's a cozier alternative: the nap. In hopes of boosting employee productivity and creativity, companies such as Ben & Jerry's, Zappos, Uber, and Google have built nap rooms at their headquarters. Some Americans still find a way to sneak in a nap even though company nap rooms are still an exception rather than a rule. One-third of American adults nap on any given day, according to a Pew Research Center report from 2009.

Daytime naps can help people who don't get enough sleep at night to be alert and motorized. "Everyone agrees that if you are sleep deprived, you can't learn, perform, or think very well," says Jerome Siegel, Ph.D., director of the Center for Sleep Research at the University of California, Los Angeles.

Kimberly Cote, Ph.D., a psychology professor at Brock University in Ontario, claims that a midday nap is beneficial for healthy adults who do get enough sleep at night. While little work has been done to examine the long-term effects of habitual napping, studies point out a variety of immediate benefits following an afternoon nap. talking about a healthy adult population, I think just about anyone could benefit from a nap," she says.

The relationship between sleep and learning

As Cote found in a 2009 review (Journal of Sleep Research, 2009), even well-rested people can benefit from naps when it comes to reaction time, logical reasoning, and symbol recognition.

Doctoral student Jennifer Goldschmied and colleagues found that people who took a 60-minute midday nap were less impulsive and more tolerant of frustration than those who watched an hour-long nature documentary instead of sleeping (Personality and Individual Differences, 2015). According to Goldschmied, emotion regulation includes frustration tolerance. It's not just about the passing of time - sleeping can give us a sense of distance [from emotional events].

Despite little understanding of how naps affect emotion regulation, Goldschmied says, napping has long been known to benefit memory and learning. "Even a brief rest helps reinforce learned material," she says.

According to Sara Mednick, PhD, a psychologist at the University of California, Riverside, the benefits of naps are substantial for many types of memory. Research has shown that people perform better on a visual texture-distinguishing task after a night of sleep than they do after waking up. In addition, Mednick and colleagues found that people performed just as well on the test after a 60- to 90-minute nap as they did after a full night's sleep (Nature Neuroscience, 2003).

"What's amazing is that a 90-minute nap can provide the same learning benefits as an eight-hour sleep period," Mednick says.

In another experiment, Mednick found that an afternoon nap was about equal to a dose of caffeine for improving perceptual learning. However, in some ways, a midday nap may be more beneficial. In her study, nappers performed better on a verbal word recall task an hour after waking than caffeine or placebo recipients (Behavioural Brain Research, 2008). According to Mednick, caffeine enhances alertness and attention, while naps also enhance some forms of memory consolidation.

Taking a catnap can also help with other memory domains. A recent study by Axel Mecklinger, PhD, at Saarland University in Germany, and colleagues examined the memory recall of volunteers who had learned meaningless word pairs and single words. After a 90-minute nap, half of the participants watched a DVD. The researchers then retested the participants' memory.

Both groups remembered about the same number of single words. This was a test of so-called item memory — the kind you use when reciting a grocery list. However, the nappers remembered significantly more of the word pairs. Unlike item memory, this type of "associative memory" involves remembering things that are related, such as putting a name with a face. And unlike item memory, the hippocampus plays a strong role in associative memory, suggesting that naps benefit hippocampus-dependent learning (Neurobiology of Learning and Memory, 2015).

Matthew Walker, PhD, a University of California, Berkeley psychologist, and colleagues recruited volunteers to test their associative memory by learning a long list of name-face pairs.

A 90-minute nap was then taken by half of the participants. In the evening, participants were given another round of learning exercises with novel pairings. Those who had not napped performed worse on the evening test compared to the morning test. However, nappers performed better on the later test, suggesting that sleep had boosted their ability to learn (Current Biology, 2011).

Behavior That Is Adaptive

However, not all nap research is so glowing. Studies have indicated that excessive sleep and daytime naps may increase levels of C-reactive protein, a marker of systemic inflammation (linked to cancer, diabetes, depression, and heart disease). Nips, however, may improve immune function, according to some research. Rebecca Spencer, Ph.D., found that the picture was almost comically muddy: Multiple studies have found that too little sleep, too much sleep, frequent naps, and infrequent naps all lead to elevated C-reactive protein levels. It is ultimately necessary to do more work. Understanding healthy sleep patterns for nighttime and daytime (Sleep Medicine, 2015).

Another concern about the downside of naps is that daytime sleep can disrupt nighttime sleep. Taking too much sleep during the day can interfere with falling asleep and staying asleep at night. According to Siegel, "one of the standard instructions at sleep disorder centers is not to nap."

In a recent study, Siegel and his colleagues looked at hunter-gatherer groups in Tanzania, Namibia, and Bolivia. He admits he's never napped himself, but his research suggests he's not the only one. They are believed to live much as we did 10,000 years ago. Although nearly all of the 94 individuals they followed took a break from the sun during midday, none of them took regular naps. In a recent study, Siegel and his colleagues looked at hunter-gatherer groups in Tanzania, Namibia, and Bolivia. He admits he's never napped himself, but his research suggests he's not the only one. They are believed to live much as we did 10,000 years ago. Although nearly all of the 94 individuals they followed took a break from the sun during midday, none of them took regular naps.

"I'm not saying we should emulate our ancestors, but napping is not a part of the ancient human physiology," Siegel says.

Siegel's subjects did not nap, but that doesn't mean naps don't work, Cote says. "Sleep is a behavior, and human behavior is highly adaptable," she says. "We sleep in many ways." It is not biologically necessary to nap after a certain age, but napping has its benefits."

Although some people may benefit more from napping than others, a certain percentage of people nap regularly. Ask these people, they will tell you they nap regularly. aware they're getting benefits: They're more alert, have better moods and they're feeling sharper," Cote says.

However, others — including Cote — wake up groggy after napping and drag the rest of the day. She believes people who nap regularly are predisposed to get more out of it. According to her own research (Biological Psychology, 2006), frequent nappers tend to perform better after a midday nap than non-nappers. "I believe we self-select this behavior," she says.

Researchers are discovering the benefits of napping. Goldschmied and colleagues found that night owl are more productive after napping than early birds.

If you're a born napper or not, your sleep cycle may play an important role. People who nap regularly seem to stay in lighter sleep stages that they can easily wake up from, while infrequent nappers tend to sink into a deeper sleep and wake up woozy, according to Mednick (who loves a nap when she can get one). A nap seems to have a qualitative difference, she says.

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