A lack of sleep and a dose of stress make a poor combination for your memory. (Photo: Microstock)

Sleep more, remember better

Sleep deprivation links to poorer memory in stressed situations.

While you sleep your mind processes memories, moving them from the short-term area to the long-term. A new Swedish study shows that your memory can serve you well after just a half night of sleep – unless you are also exposed to stress.

“Although a night with little sleep might not affect memory, it can be impaired if a lack of sleep in combined with acute stress,” says Christian Benedict of Uppsala University’s Department of Neuroscience.

He teamed up with Jonathan Cedernaes on a study which is now to be published in the journal Sleep.

The two researchers think more should be done to ensure that we get enough sleep.

“Steps to help people with sleeping problems can be absolutely essential. For example school days could start later in the morning or more flexible working hours could be initiated,” says Benedict.

He thinks such initiativers would help people remember better in stressed situations. They could perform better at work or at school.

Whole nights and half nights

The two researchers used easy games to study memories after subjects awoke from nocturnal sleep.

Fifteen participants took part in two shifts at a sleep clinic. In the first test, the 15 healthy young men studied a computer screen displaying 15 pairs of cards. Then some of them were allowed to sleep eight hours, from 11 PM to 7 AM, while the others were only allowed to sleep from 3 AM to 7 AM. The next morning they were to try and find as many of these same pairs as they could on the computer.

The researchers experienced that the ones who had only a half night of sleep initially did just as well as the ones who had slept eight hours or so. But not when subjected to stress.

The test was also repeated after the subjects were cognitively stressed for 30 minutes. They were asked to recall a bunch of words that they had just learned while simultaneously being subjected to disturbing background noise.

When the test was repeated it was found that the participants who had only slept half of the recommended eight hours performed 10 percent worse on the test. The memories of the ones who had slept the entire night were not affected by the stress.

Sleep secures memories

It is well known that sleep and memory are tightly connected. Ståle Pallessen, a psychology professor at the University of Bergen, explains that our brain is much less disturbed by external phenomena while we sleep and thus is freer to consolidate memories.

“By consolidation I mean that permanent structural changes in the brain occur which form the basis for memory. Permanent changes are made in the connections between neurons,” explained Pallessen to ScienceNordic’s Norwegian partner, forskning.no.

This means that sleep disorders can have negative consequences for memory and learning.

The Swedish project only investigated the effect of one night of insufficient sleep.

“An important next step will be to investigate how chronic insomnia and chronic stress combine to undermine the ability to remember facts,” says Benedict in a press release.


Read the Norwegian version of this article at forskning.no

Translated by: Glenn Ostling

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