Study: More Sleep, Sharper Brain

Jan. 21, 2004 -- Everybody feels refreshed following a good night's sleep. Butcan you wake up smarter? More artistic perhaps?

German scientists say they have demonstrated for the first timethat our sleeping brains continue working on problems that baffleus during the day, and the right answer may come more easily aftereight hours of rest.

The German study is considered to be the first hard evidencesupporting the common sense notion that creativity and problemsolving appear to be directly linked to adequate sleep, scientistssay. Other researchers who did not contribute to the experiment sayit provides a valuable reminder for overtired workers and studentsthat sleep is often the best medicine.

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

"A single study never settles an issue once and for all, but Iwould say this study does advance the field significantly," saidDr. Carl E. Hunt, director of the National Center on SleepDisorders Research at the National Institutes of Health.

"It's going to have potentially important results for childrenfor school performance and for adults for work performance," Huntsaid.

Sleepers Solve Problems Better

Scientists at the University of Luebeck in Germany found thatvolunteers taking a simple math test were three times more likelythan sleep-deprived participants to figure out a hidden rule forconverting the numbers into the right answer if they had eighthours of sleep. The results appear in Thursday's issue of thejournal Nature.

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

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

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

Jan Born, who led the study, said the results supportbiochemical studies of the brain that indicate memories arerestructured before they are stored. Creativity also appears to beenhanced in the process, he said.

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

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

Better Memory

The results also may explain the memory problems associated withaging because older people typically have trouble getting enoughsleep, especially the kind of deep sleep needed to processmemories, Born said.

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

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

History is dotted with incidents where artists and scientistshave awakened to make their most notable contributions after longperiods of frustration. For example, that's how Russian chemistDmitri Mendeleev established the periodic table of elements andBritish poet Samuel Taylor Coleridge wrote his epic "Kubla Khan."

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

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

The results "give us good reason to fully respect our periodsof sleep — especially given the current trend to recklessly curtailthem," they said.