The more we understand about sleep, the more apparent it becomes that getting enough sleep is as important to our wellbeing and long term health as eating healthy and being active. Not getting enough sleep affects both our bodies and our minds, increasing our risk of serious health problems like diabetes and heart disease and impacting how we process information and our mood. New research indicates that sleep may also play a big role in how we learn and how we store information into our memory for later retrieval.
One of the studies behind this new research was conducted by a team from several different academic institutions and funded by the National Institutes of Health. It looked at how time of day and sleep impacted the ability of a group of students to recall a specific set of information. The results show that sleep plays a role in storing new information for later retrieval and that the proximity between intake of the new information and sleep is a determining factor. To gain insight into how sleep and memory are intertwined, the research team gathered a group of more than 200 students and split them into two groups. Each group was asked to learn two different sets of word pairs, one where the two words in each pair were related and one where they were not. Each group completed this assignment on a different time schedule, one learning their word pairs in the morning and one learning them at night. The students were then tested three different times to gauge their recall. The first test was conducted 30 minutes after learning the word pairs, the second 12 hours later, and the third after 24 hours. The setup of the study is important because it allowed the team to see many different facets of the sleep-learning-memory connection with a single set of data.
First, they were able to see that the time of day someone learned something had little bearing on their immediate recall. The results of the 30 minute test were similar for both groups and for both types of word pairs.
Second, they were able to see how sleep impacted the results of the second test as the students who learned the word pairs in the morning took the second test without a night’s sleep between learning the word pairs and taking the second test. The students who learned the word pairs at night got a full night sleep between the first test and the second test. The result was that overall recall was better after a full night’s sleep than it was after being awake all day.
Third, they were able to see if recall was still affected after both groups had gotten a full night’s sleep. The result here was interesting as those students who learned the word pairs at night and therefore closer to the time they went to sleep still had better recall of the word pairs after 24 hours than their peers who learned the word pairs in the morning. This shows that new information may be more easily stored or readily recalled when it is learned in close proximity to going to sleep.
Lastly, by using the two different types of word sets the research team was able to see if different types of memory and recall were impacted differently. Learning related word pairs is easier because the two words already have a connection. Learning unrelated word pairs requires a different kind of effort because we must create new associations in order to remember the pairs properly. The study showed that the ability to remember the unrelated pairs was dependent on when the pairs were learned. The closer the learning was to going to sleep, the better the student was able to recall the unrelated pairs. Recall of related pairs was unaffected.
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