Middagdutje verbetert leerprestaties*
Mensen die overdag een dutje doen slagen er daarna beter in om nieuwe informatie uit hun hoofd te leren. Dat blijkt uit een kleine Amerikaanse studie onder 39 deelnemers.
Onderzoekers van de Universiteit van Californië gaven de deelnemers twee keer een
opdracht waarbij er feiten uit het hoofd geleerd moesten worden. De eerste opdracht voltooide iedereen 's ochtends. Voorafgaand
aan de twee leertaak die 's middags plaatsvond, mocht de helft van de deelnemers een dutje van negentig minuten doen.
Na afloop van het experiment bleek dat alle proefpersonen bij de eerste leertaak ongeveer even goed presteerden. Bij de tweede
leeropdracht onthielden de mensen die een middagdutje hadden gedaan veel meer informatie dan de proefpersonen die niet hadden geslapen.
De wetenschappers brachten tijdens het onderzoek ook de hersenactiviteit van de proefpersonen in kaart. Uit die
metingen maakten ze op dat een middagdutje er waarschijnlijk voor zorgt dat 'feitelijke' herinneringen uit het kortetermijngeheugen
in de hippocampus worden verplaatst naar de zogenaamde prefrontale cortex in de hersenen.
"Je kunt de hippocampus vergelijken met de inbox van je e-mail", verklaart hoofdonderzoeker Matthew Walker"Als de inbox vol is, kun je geen nieuwe mail ontvangen totdat je gaat slapen en alle e-mails
verwijderd zijn."
Researchers Explore the Benefits of Sleep--and the Problems with Sleep-Deprivation
SAN DIEGO-A panel of researchers with expertise in infant learning, adolescent drug use, aging, and memory convened for a symposium at the AAAS Annual Meeting, and as they described their research in detail, the conclusion was inescapable:
America, you need a nap.
"People are definitely sleep-deprived," Sara Mednick, an assistant professor of psychiatry at the University of California, San Diego, said in a AAAS podcast.
"That sleep-deprivation is leading to increased risk for cardiovascular disease, depression, mood problems, weight gain, obesity, and diabetes. A lot of different health concerns seem to be helped by good sleep and damaged by poor sleep."
The Sunday morning symposium-"Role of Sleep in Memory from Development to Old Age'-and a related press briefing drew extensive international news
coverage.
The Economist had a trans-Atlantic take, suggesting that many Europeans who favor an afternoon siesta may be right after all.
"It has already been established that those who siesta are less likely to die of heart disease," says the Economist. "Now, Matthew Walker and his colleagues at the University of California, Berkeley, have found that they probably have better memory, too. An afternoon nap, Dr. Walker has discovered, sets the brain up for learning."
An article at PsychCentral.com elaborated on that notion, describing research conducted at Berkeley that examined the effects of a nap on the brains of 39 healthy adults. Half of them took a 90-minute nap during the day, and then all were tested to measure cognitive ability.
"Those who took the nap outperformed subjects who did not," the article said. "The people who had a nap improved their ability to learn by 10%, according to the
researchers.
"Sleep not only rights the wrong of prolonged wakefulness, but, at a neurocognitive level, it moves you beyond where you were before you took a nap," Walker said.
Michael Torrice, writing for ScienceNow, focused on teens and their outsized need for sleep. He cited the presentation by UC-San Diego political scientist James Fowler, who studied a network of more than 8000 seventh- to 12th-grade students and their sleeping and marijuana-smoking habits.
"When one teenager starts sleeping less, her friends and others in her social circle soon lose sleep, too, according to new research…," Torrice writes. "This lack of sleep not only produces groggy high-school students but also can lead to drug use, the researchers reported."
It's commonly assumed that older people need less sleep, but that's a misconception, according to Richard Alleyne's story in the U.K.-based Independent. He cited Sean Drummond, an associate professor in the UCSD psychiatry department, who said at the AAAS symposium that while an older person's sleep might be more frequently disrupted, they still need just as much as a younger person.
"Older adults benefit from getting as much sleep as they got when they were in their 30s," Drummond said. "This varies from person to person, but whatever you slept when you were 35 should be the same from 75…The quality of sleep may go down, but they must maintain the quantity. This will have relevance to age-related cognitive decline."
Xinhua, the Chinese news agency, also had a brief story on the symposium that extolled the benefits of a nap.
Mednick, talking to Nicole Foley in the AAAS podcast, said that the length of a nap was associated with certain benefits. Motor-memory is supported by a quick 20-minute power-nap, while verbal memory and the ability to recall, say, a grocery list, are supported by a deeper nap lasting 30-60 minutes. A nap of 60 to 90 minutes aids visual and perceptual learning, unconscious learning, and creativity.
"For me," Mednick said, "the ideal nap is 90 minutes. I try to take as many 90-minute naps in the week as a can." But she allowed that it's not always possible to meet the goal. She's got a new baby, and the baby's not much of a
napper. (Februari 2010)
