We’ve all been there: After struggling over a problem for hours, we rest our eyes for a few minutes and suddenly the answer is lying before us, clear as day.
This common phenomenon has contributed to the idea of the so-called power nap, a quick snatch of rest that stops short of deep sleep yet somehow manages to refresh and stimulate. Although there is much about the power nap that remains a mystery, researchers have begun to uncover the brain processes behind the little miracles it produces.
The latest research, presented today at an annual meeting of neuroscientists, may help explain the mental spark that sometimes occurs during a nap. Researchers monitoring the brain activity of 15 at-rest individuals found that the right side of their brain -- the hemisphere most associated with creativity -- chattered busily to itself as well as to the left hemisphere, which remained relatively quiet.
“The right side of the brain was better integrated,” says study author Andrei Medvedev, Ph.D., an assistant professor at Georgetown University’s Center for Functional and Molecular Imaging, in Washington, D.C.
Medvedev had expected the left side of the brain to be better integrated, since that hemisphere tends to be dominant in right-handed people (and vice versa in left-handed people). All but two of the study participants -- and fully 95 percent of the general population -- are right-handed.
The division of labor between the right and left sides of the brain isn’t as clear-cut as once thought. Generally, though, the right hemisphere is associated with creative tasks, such as visualization and big-picture thinking, while the left is more analytic, specializing in numbers and language processing.
It’s not yet clear how, or if, the new study results fit into this framework. But Medvedev speculates that the right brain may be performing important “housecleaning” tasks during a nap. The most important of these is probably the consolidation of memories, although other tasks are probably involved as well, he says.
This hypothesis jibes with the current understanding of the essential role that sleep plays in memory formation, says Suresh Kotagal, M.D., a professor of neurology at the Mayo Clinic in Rochester, Minnesota.
“We are exposed to certain pieces of information, but if we get to sleep on it, the sleep seems to facilitate the transfer of information from the short-term memory bank into the more permanent memory bank,” says Kotagal, who was not involved in the study.
Jonathan Friedman, M.D., director of the Texas Brain and Spine Institute, in Bryan, says the new findings come at a time of growing interest in the neuroscience of sleep.
“Emerging scientific evidence suggests that naps -- even very short ones -- significantly enhance cognitive function,” Friedman says. “Increasing understanding of how sleep improves brain function may someday allow us to harness this effect, and the current study may open one of many doors in this regard.”
Medvedev and his colleagues used a type of brain imaging known as near-infrared spectroscopy, which involves placing optical fibers similar to electrodes symmetrically around a person’s scalp. These “optodes” send infrared light through the brain and measure how much light returns.
The intensity of light bouncing back provides an estimate of the blood flow in different regions of the brain. Blood flow, in turn, is an indicator of how active those regions are.
The study results, which Medvedev presented at the Neuroscience 2012 meeting in New Orleans, should be considered preliminary. They haven’t been peer-reviewed by other experts in the field, and they’ll need to be replicated in other studies before firm conclusions can be drawn.
But they do shine a light -- infrared light, in this case -- on how the two sides of our brain interact when we’re at rest. “This may change our perspective of the brain,” Medvedev says. “We may just conclude that the sub-dominant part of the brain may also be important.”
Power Naps May Boost Right-Brain Activity was originally published on Health.com
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To Nap Or Not To Nap?
If you've got a big project you have to really focus on, or especially if you have to drive, hit the hay. If the rest of the workday looks like smooth sailing, or you often have trouble sleeping at night, skip the nap. "Naps are sort of a double-edged sword," warns Dr. Epstein. "If you're indeed sleepy and it's going to interfere with your performance, the best way to get over that is to go to sleep. But if you have trouble sleeping at night, taking a nap can be a problem, because if you sleep in the daytime you won't sleep at night." You've also got to be tired enough to fall asleep during the day. "Well-rested people don't have the ability to power nap and that's great," says Maas. "It's much better to get good nocturnal sleep and not be able to than to <em>have</em> to power nap. While we do have a natural dip in our circadian rhythms that usually occurs in the afternoon, that is exacerbated by not having good nocturnal sleep."
What's The Best Time For A Nap?
Because of the natural cycles of our circadian rhythms, we are at our most tired twice during a 24-hour period. One peak of sleepiness is usually in the middle of the night, so the other, 12 hours later, falls smack-dab in the middle of the afternoon. "It's not that [there's] a good time to get the nap, it's that's the time you're going to be sleepy," explains Dr. Epstein. "It's a physiologic basis for a siesta," he says, and also why so many of us feel a slump around that time and head for the coffeemaker. If you get enough sleep at night, chances are you won't be bothered by the mid-afternoon peak of sleepiness. But if you're sleep-deprived, you'll feel that "sleep debt" greater in the afternoon, and be more inclined to nap.
Where Should You Nap?
"The more comfortable you can get, the easier it is to fall asleep," says Dr. Epstein. That could mean closing your office door and dimming the lights, or finding an unused conference room, parking yourself on a common area couch, or even just putting your head down on your desk, he says. But sleep-chasers should also get creative. Many large companies, especially in their headquarters, have infirmaries or other first-aid offices. Maas suggests calling to see if they have any available beds. Or, in warm climates, lie down for a few minutes on a bench outdoors. Desperate? "Even restrooms give you an opportunity to sit for 10 minutes," he only half-jokes. Better still, try heading out for a nap on your next "lunch" break -- no one has to know you're not actually eating! "A lot of workers are kind of sneaky in these naps, they'll go out to the parking lot and take a quick snooze," says Maas, but most are allowed (if not legally required) to take a break during the day. Or, head to a local spa that provides nap rooms for a fee. Locations are popping up <a href="http://money.cnn.com/2008/08/21/smallbusiness/naps_for_sale.fsb/index.htm" target="_hplink">in numerous cities</a>, reports CNN Money.
What Else Do You Need?
The same sleep hygiene rules apply to naps as to nighttime rest, namely that you want the environment to be quiet, dark and cool, says Maas. That might mean bringing an eye mask or ear plugs to work, he says, especially if you're opting for a nap on a communal couch.
How Long Should You Nap?
Maas's definition of the power nap calls for only 10 to 15 minutes of rest, but Dr. Epstein says even up to 30 can still be beneficial. However, sleep much longer than that and you'll enter deep sleep, leaving you feeling groggy when you wake up, warns Maas. If you really need more than 15 minutes of shuteye, you're better off shooting for a full 90 to guarantee waking up feeling refreshed, as that's how long it takes your body to complete an entire REM cycle, he explains. So set a cell-phone alarm and then get back to business.
Should You Skip Caffeine?
"Caffeine acts as a way to avoid sleepiness, but it's not a replacement for sleep," says Dr. Epstein. If you have a big project to focus on in the afternoon, caffeine can help you power through the work, but it won't do anything to chip away at your sleep debt, he explains. Plus, if you resort to caffeine too late in the day you risk messing with your nighttime sleep. As long as you're four to seven hours away from bedtime, there's no real need to skip your afternoon pick-me-up, even if you're going to steal away for some zzz's. In fact, <a href="http://www.sciencedaily.com/releases/2010/05/100511192248.htm" target="_hplink">caffeine can even improve your performance</a> later in the day. It takes some time for the caffeine to kick in, so some experts suggest what's been dubbed a "caffeine nap" -- drinking a cup of coffee before a 20-minute nap, then waking up to "maximum alertness," says Dr. Epstein.
Boss Won't Go For It?
Smart, educated companies are catching on to the fact that sleepy employees are bad for their bottom line and promoting short breaks as a potential solution. If your boss is at the other end of the spectrum, presenting the facts might be a good idea. Many corporations are already promoting preventive health and wellness programs focused on exercise and nutrition, says Maas, so why not add sleep? "They've got to realize that there are three things that determine longevity: nutrition, exercise we're already doing a lot about, but we're totally ignoring the third component, which is sleep," says Maas. "Sleep is treated as a luxury in American society, and it's a necessity."