Want to maximize your learning capacity? Get some sleep. That’s the takeaway from a study that examined the influence of sleep and time of day on learning and memory. This latest research is another piece of compelling evidence that sleeping helps to strengthen our ability to learn new things, and to convert new learning into longer-term memories.

In this study, 207 students who slept regularly for at least six hours per night were assigned to learn two different sets of word pairs. One set of word pairs were semantically related; the other pairs were made up of unrelated words. The difference is important. The type of learning involved in recalling unrelated word pairs is different than for pairs that are related, and involves forming new associations, essentially creating a relationship in the mind for these words that are otherwise un-related.

The students were assigned to study the word pairs at one of two times: 9 a.m. or 9 p.m. After an initial study period to learn the two types of word pairs, the students were re-tested after 30 minutes, then again after 12 hours, and a final time after 24 hours. The students who did their learning in the evening went to sleep for their regular nightly rest relatively soon after their initial study period. The daytime learning students, on the other hand, spent a normal day of wakefulness before going to bed as usual that evening.

This allowed researchers to assess the influence of time of day on learning. It also allowed them to examine how the proximity of sleep to learning might have an influence.

What did they find?

Time of day had no effect on performance and initial memory (at the 30 minute test). This was true for both types of word pairs.

After 12 hours, overall memory was better after a night’s sleep than for those who spent the day awake

After 24 hours, researchers found that students who went to sleep shortly after learning had better memory of what they learned than those who did their learning followed by a day of wakefulness before sleep.

The different types of word pairs—and the two types of learning they required—fared differently depending on sleep. Memory for related word pairs was not affected by how soon sleep followed learning. Memory for the un-related word pairs—the kind that required making new associations—was stronger for students who slept shortly after learning than for those who spent the day awake.

The deterioration of memory during the wake period was less when students had slept shortly after learning.

These results indicate that sleep is most helpful to memory when it happens soon after learning new things. Sleep seems to have a stabilizing effect on newly learned information, rooting it into memories that last and clearing the way for new information to be processed.

This latest research joins a series of recent breakthroughs in the study of sleep and memory.

In this study, researchers used fruit flies to test the links between sleep and the creation of long-term memories. After breeding fruit flies to sleep on demand, researchers exposed the flies to new information. All of the flies retained their new knowledge for a short period of time, but only the flies that slept after learning appeared to convert their short-term knowledge to long-term memory.

Another study showed how sounds heard during sleep may help to direct and enhance memory. Participants learned a spatial puzzle that involved moving images to specific places on a computer screen. While doing this, they heard sounds that corresponded to specific images. During sleep, the study subjects were exposed to half of those same sounds. When they performed the puzzle again from memory after sleeping, they were better able to recall the placement of images whose sounds they’d heard during sleep.

This study showed how naps can boost brain power. Two groups of young adults learned the same task. One group napped after learning; the other didn’t. Six hours after learning the initial task, both groups were asked to learn brand new material. The non-napping group scored lower than they had on their initial learning exercise, while the napping group actually improved their performance compared to their first one.

Sleep doesn’t only enhance memory. It also appears to diminish the emotional impact of painful memories. In a study I wrote about recently, two groups were exposed to emotionally charged images. Both groups saw the images twice, in viewings twelve hours apart. One group slept in between viewings and the other did not. Those who slept reported feeling less of an emotional reaction to the images at their second viewing, compared to the group who did not sleep. MRI scans showed decreased activity in the region of the brain that processes emotions for the group who slept.

We’re learning more all the time about how sleep helps us learn and retain information, how it clears the mind and prepares us to learn new things, as well as how it may protect us from the emotional pain of difficult memories.

Whether you’re prepping for a test, starting a new job, coping with difficult circumstances, or just want to feel more agile of mind, the prescription is the same: get some sleep!

Sweet Dreams,

Michael J. Breus, PhD

The Sleep Doctor™


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Everything you do, you do better with a good night’s sleep™

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