Sleeping enough is important for memory. During sleep, the brain transfers the day’s new information from short-term memory to long-term memory. Research has demonstrated that sufficient sleep is critical to this process. A new study from Uppsala University adds a caveat: insufficient sleep does not hamper memory formation, as long as there is no cognitive stress. That is, the researchers found that people who slept for only a short time, followed by a cognitively stressful situation had reduced recall. The findings indicate the importance of sleeping enough before facing stressful situations like school or work.
The researchers conducted two experiments to investigate the role of nocturnal sleep on memory transfer and how stress affects that relationship. In the first experiment, the researchers asked participants to learn the locations of 15 card pairs on a computer screen during an evening learning session. Afterwards, participants slept for a short duration (four hours) or a long duration (eight hours). The next morning, the researchers tested the participants’ ability to recall the card pair locations. Both groups of participants—the short sleepers and the long sleepers—were equally effective in recalling the pair locations.
In the second experiment, the participants completed the same learning task and then slept for a short or long period. The next morning, the participants were acutely stressed for 30 minutes before completing the recall exercise. The participants who slept only four hours performed 10 percent worse than those who got a full night’s sleep.
The results indicate that the brain can compensate for either stress or insufficient sleep, not both.
“Interventions such as delaying school start times and greater use of flexible work schedules, that increase available snooze time for those who are on habitual short sleep, may improve their academic and occupational performance by ensuring optimal access to memories under stressful conditions” stated Jonathan Cedernaes, study co-author and researcher in Uppsala University’s Department of Neuroscience.
This research is published in the journal Sleep.
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