Naps help us retain information: study
Research finds that sleeping allows brain to remember what it has learned
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 60to 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 decision-making 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.