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8 hours sleep - that's what your brain needs if you want it to perform at its best
 
 
 
'Sleeping on it' really can solve problems

21 January 04
NewScientist.com news service

A tricky problem really can be solved by "sleeping on it", new experiments have shown. The researchers suggest our brains re-juggle data while we slumber to present us with a solution when we wake.

Anecdotal evidence has long suggested that a night's rest can bring clarity to a complex dilemma. For example, the Russian chemist Dmitri Mendeleyev devised the periodic table following a moment of nocturnal "insight". "He said he had a dream where all the elements fell down in the right positions," says Ullrich Wagner at the University of Lbeck in Germany.

In the experiments conducted by Wagner and his colleagues, volunteers tackled arithmetic problems and then took an eight-hour break. Those who slept during the break were twice as likely to realise that there was a hidden rule that substantially simplified the calculations.

"We think the strongest explanation is that sleep acts on the patterns created during the training, restructuring them to give insight to the hidden rule," says Wagner.

He thinks the data is sifted in the hippocampus and the prefrontal cortex, areas of the brain which store and analyse memories. The team hopes next to scan the brains of people doing similar problems to spot which brain areas distinguish states of "insight" and "non-insight"

Sleepers and wakers

The arithmetic problem set for the volunteers required transforming a sequence of numbers into a second sequence by applying two simple rules. But they were only to provide the final number in the second sequence.

The hidden rule was that the final number in the second sequence was in fact always the same as the second number. Realising this would mean the volunteers could save a lot of needless calculation.

Only one of the three groups of 22 volunteers was allowed to sleep during the interlude between training and re-testing. The other two groups remained awake, one during the day and one at night, to rule out "circadian" rhythm effects.

The "sleepers" were more than twice as likely as the "wakers" to spot and exploit the short cut. "We recorded all the responses, and we could see very clearly the 'Eureka moment'," says Wagner.

In an accompanying experiment, the team also showed that the poor performance of the "wakers" was not simply because they were tired.

Journal reference: Nature (vol 427, p 352)
 
 
Study confirms sleep essential for creativity

Everybody feels refreshed following a good night's sleep. But can you wake up smarter? More artistic perhaps?

German scientists say they have demonstrated for the first time that our sleeping brains continue working on problems that baffle us during the day, and the right answer may come more easily after eight hours of rest.

The German study is considered to be the first hard evidence supporting the common sense notion that creativity and problem solving appear to be directly linked to adequate sleep, scientists say. Other researchers who did not contribute to the experiment say it provides a valuable reminder for overtired workers and students that sleep is often the best medicine.

Previous studies have shown that 70 million Americans are sleep-deprived, contributing to increased accidents, worsening health and lower test scores. But the new German experiment takes the subject a step further to show how sleep can help to turn yesterday's problem into today's solution.

"A single study never settles an issue once and for all, but I would say this study does advance the field significantly," said Dr. Carl E. Hunt, director of the National Center on Sleep Disorders Research at the National Institutes of Health.

"It's going to have potentially important results for children for school performance and for adults for work performance," Hunt said.

Scientists at the University of Luebeck in Germany found that volunteers taking a simple math test were three times more likely than sleep-deprived participants to figure out a hidden rule for converting the numbers into the right answer if they had eight hours of sleep. The results appear in Thursday's issue of the journal Nature.

The study involved 106 people divided into five separate groups of equal numbers of men and women ages 18 to 32. One group slept, another stayed awake all night, and a third stayed awake all day for eight-hour periods before testing following training in the main experiment. Two other groups were used in a supplemental experiment.

The study participants performed a "number reduction task" according to two rules that allowed them to transform strings of eight digits into a new string that fit the rules. A third rule was hidden in the pattern, and researchers monitored the test subjects continuously to see when they figure out the third rule.

The group that got eight hours of sleep before tackling the problem was nearly three times more likely to figure out the rule than the group that stayed awake at night.

Slow wave to solving problems

Jan Born, who led the study, said the results support biochemical studies of the brain that indicate memories are restructured before they are stored. Creativity also appears to be enhanced in the process, he said.

"This restructuring might be occurring in such a way that the problem is easier to solve," Born said.

Born said the exact process in the sleeping brain for sharpening these abilities remains unclear. The changes leading to creativity or problem-solving insight occur during "slow wave" or deep sleep that typically occurs in the first four hours of the sleep cycle, he said.

The results also may explain the memory problems associated with aging because older people typically have trouble getting enough sleep, especially the kind of deep sleep needed to process memories, Born said.

"Even gradual decreases in the total time for slow wave sleep and deep sleep is correlated to a kind of decrease in memory function, and in turn to a decrease in the ability to recognize hidden structures or the awareness of such things," Born said.

Other researchers said they have long suspected that sleep helps to consolidate memories and sharpen thoughts. But until now it had been difficult to design an experiment that would test how it improves insight.

History is dotted with incidents where artists and scientists have awakened to make their most notable contributions after long periods of frustration. For example, that's how Russian chemist Dmitri Mendeleev established the periodic table of elements and British poet Samuel Taylor Coleridge wrote his epic "Kubla Khan."

Born and his team "have applied a clever test that allows them to determine exactly when insight occurs," wrote Pierre Maquet and Perrine Ruby at the University of Liege in a commentary on the research, also published in Nature.

Maquet and Ruby both say the study should be considered a warning to schools, employers and government agencies that sleep makes a huge difference in mental performance.

The results "give us good reason to fully respect our periods of sleep -- especially given the current trend to recklessly curtail them," they said.