Many people feel that taking a short nap during the day enhances their creativity. They struggle with a problem for hours without finding a solution, take a short nap, and suddenly the solution becomes clear to them. Although this is a common experience, exactly how it might work has remained a mystery for scientists, because technically short naps don’t provide the deep level of rest that they associate with a full night’s sleep and its rejuvenating effects.
A new study presented at the Neuroscience 2012 meeting in New Orleans may shed light on how “power naps” work. Professor Andrei Medvedev of Georgetown University used the new technique of near-infrared spectroscopy to monitor the brain activity of 15 subjects while they were napping. This type of imaging involves the placement of a number of optical fibers around the subject’s scalp; these fibers then project infrared light into the brain and measure how much of it returns from each area. The intensity of light as it bounces back gives a clear picture of the blood flow in various brain regions, which in turn gives a good indication of how active those regions are.
The images showed that during naps the right hemisphere of the brain – associated with creative tasks – became active during the nap periods, while the left hemisphere remained more at rest. The right side of the brain was, in fact, “chattering” to itself during the nap, as well as communicating with the resting left side of the brain.
Naps may allow the brain to do some housekeeping
Medvedev theorizes that what may be happening is that during these “power naps” the right side of the brain may be performing important “housekeeping” duties that facilitate the translation of short-term memories into more permanent memories. As one reviewer of the study at the Mayo Clinic put it, “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.”
A second study performed by Matthew P. Walker of UC Berkeley found similar results. 39 college students were asked to learn a series of names and faces at noon, and then were tested a few minutes later to see how many they remembered. Then they were tested again at 6 p.m. the same day, with half of the students taking a 90-minute nap in between. The students who took naps performed much better on the memory tests than those who did not, who in fact showed a significant decline in their scores. The researchers found that the students’ improved performance on the 6 p.m. test was correlated with stage 2 non-REM sleep, the state that occurs between restful deep sleep and the state of restful eye movement (REM) sleep. “It wasn’t just the total amount of sleep, but a particular type of sleep that was facilitating improvements.”
As for how this works, Walker agrees with Medvedev’s “housekeeping” theory, although he proposes a different metaphor to explain it. He suggests thinking of the part of your brain where short-term memories are stored like an email inbox. “When you sleep,” he says, “essentially what you may be doing is clearing out that inbox to another folder, so you have a refreshed capacity to receive new emails.” The naps may have been particularly effective for the students, Walker says, because students tend not to get enough sleep at night: “They’re up late studying and having a good time.” The naps may enable them to catch up on some of the sleep deprivation they have built up over time. If you’re getting adequate rest at night, you might not need the naps.
Naps work for many but may be problematic for others
Although short “power naps” clearly help many people to improve their creativity, problem-solving abilities, and memories, for those with existing sleep disorders napping may be problematic and even counter-productive.
For example, people with chronic insomnia who have trouble getting enough sleep might find that naps perpetuate their bad sleep habits, and make it even more difficult for them to fall asleep at night. The naps have the effect of reducing their nighttime sleep drive, and thus become just another episode of fragmented sleep. People who suffer from sleep apnea and as a result don’t get enough deep rest at night also may not benefit from naps, because the same condition that causes them to stop breathing for short periods of time during nighttime sleep and thus not get enough rest will also occur during naps.
But many people do benefit from taking naps, and those benefits have now been scientifically validated, both in terms of brain activity and improved performance on memory tests. So if your schedule allows it, give the “power nap” approach a try, because it might work for you. If you’re at work, however, you might an appropriate place to do it, because if your boss finds you snoozing with your head on your desk, showing him this article might not be enough to convince him that you’re doing it to improve your productivity.