Quick shut-eye boosts brain power

Re­search finds that sleep­ing al­lows brain to re­mem­ber what it has learned

Calgary Herald - - NEWS - LINDA BLAIR

When you can’t solve a prob­lem, have you tried putting it aside un­til the next day? If so, did you know the so­lu­tion as soon as you woke up?

This is no co­in­ci­dence. There’s plenty of ev­i­dence that sleep ben­e­fits all sorts of learn­ing — and, as a Har­vard study demon­strated, a 60- to 90-minute nap can do the job just as ef­fec­tively as sleep­ing all night.

St­ef­fen Gais and col­leagues at the Uni­ver­sity of Lubeck an­a­lyzed declar­a­tive me­mory (abil­ity to re­call facts), and found that stu­dents who had a quick shut-eye after learn­ing vo­cab­u­lary re­mem­bered the words bet­ter.

At the Uni­ver­sity of Parana in Brazil, Felipe Bei­jamini and col­leagues stud­ied par­tic­i­pants’ log­i­cal prob­lem-solv­ing abil­ity be­fore and after sleep. Some par­tic­i­pants took a nap after try­ing to solve a video game prob­lem, while oth­ers took a break, but didn’t sleep. When retested, those who had napped were al­most twice as likely to be able to solve the prob­lem.

Sleep also en­hances ana­log­i­cal prob­lem-solv­ing, the skill that al­lows us to take in­for­ma­tion we’ve learned in one do­main, and ap­ply it ef­fec­tively to other ar­eas.

A good ex­am­ple of this is a study car­ried out by Hi­uyan Lau and col­leagues at City Uni­ver­sity in New York.

They taught par­tic­i­pants the English mean­ings of some Chi­nese char­ac­ters, then chal­lenged them to ap­ply what they ’d learned to other se­man­ti­cally sim­i­lar Chi­nese char­ac­ters. Those who napped be­fore the chal­lenge did bet­ter than the oth­ers.

This is a con­vinc­ing body of ev­i­dence, then, but there re­mains a lim­i­ta­tion — that in all th­ese stud­ies, par­tic­i­pants were aware of what they were meant to be learn­ing.

Could sleep also help us to re­tain in­for­ma­tion we aren’t even aware we’ve taken in?

It seems so, ac­cord­ing to a new study from the Uni­ver­sity of Bris­tol, which pre­sented par­tic­i­pants with a con­trol task and a masked prime task (MPT), tested them after a 90-minute nap, and on an­other oc­ca­sion, after 90 min­utes of wake­ful­ness.

In the con­trol task, par­tic­i­pants were asked sim­ply to re­spond as soon as they saw a red or blue square on a screen, whereas in the MPT they had to de­cide whether words pre­sented briefly were “good” or “bad.”

What they didn’t know was that just be­fore they were shown the test word, they were shown an­other word — so quickly they weren’t aware of it. Th­ese “prim­ing ” words were de­signed to af­fect de­ci­sion­mak­ing time.

Us­ing both phys­i­o­log­i­cal mea­sures of brain ac­tiv­ity and test scores, the re­searchers dis­cov­ered that par­tic­i­pants were pro­cess­ing the primed words while they napped — words they didn’t even know they’d seen.

This pro­vides fur­ther ev­i­dence for the value of tak­ing a nap or go­ing to bed soon after learn­ing things you hope to re­tain.

How­ever, the re­sults im­ply some­thing else as well, some­thing more cau­tion­ary.

If you use your screens just be­fore bed­time, when you fall asleep, you’ll prob­a­bly process and re­tain not just what you were aware of see­ing, but all the pe­riph­eral sug­ges­tions in the ad­ver­tise­ments and pop-ups, as well.

Re­search shows that nap­ping after learn­ing some­thing new helps the brain re­tain and process the in­for­ma­tion.

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