Getting a good night's sleep has become one of the major health obsessions of our times. Researchers have recently pointed out that a lack of sleep can affect everything from our feeling of gratefulness about our lives to our risk for gaining weight.
Now, new neuroscience research out of the University of California, Berkeley, appears to shed light on how poor sleep patterns may contribute to memory loss as we age.
In a release, sleep researcher Matthew Walker explains that the "slow brain waves" generated during the kind of deep sleep we enjoy in youth helps the brain transport memories from the short-term storage of the hippocampus to the prefrontal cortex's longer-term "hard drive." As we age, our quality of sleep deteriorates, so memories may not be be shifted to our long-term memory as efficiently.
"What we have discovered is a dysfunctional pathway that helps explain the relationship between brain deterioration, sleep disruption and memory loss as we get older – and with that, a potentially new treatment avenue," wrote Walker, an associate professor of psychology and neuroscience and an author of the study, which appears in the journal Nature Neuroscience.
According to the release, the research team tested the memory of 18 healthy young adults (mostly in their 20s) and 15 healthy older adults (mostly in their 70s) after a full night's sleep hooked up to an electroencephalographic (EEG) machine which measured their brain-wave activity. Before they went to sleep, all participants learned and tested on 120 word sets.
After they woke up, they were all tested again on the word pairs while their brains were being scanned using functional and structural Magnetic Resonance Imaging (fMRI).
"In older adults, the results showed a clear link between the degree of brain deterioration in the middle frontal lobe and the severity of impaired 'slow-wave activity' during sleep. On average, the quality of their deep sleep was 75 per cent lower than that of the younger participants, and their memory of the word pairs the next day was 55 per cent worse."
Ken Paller, a professor of psychology and the director of the cognitive neuroscience program at Northwestern University in Evanston, Ill., who was not involved in the research, told the New York Times that memory function may also be enhanced by things like exercise.
But he did say that the study told "a convincing story, I think: that atrophy is related to slow-wave sleep, which we know is related to memory performance. So it's a contributing factor."
Understanding this connection may lead to targeted treatments using brain stimulation or drugs to improve sleep and, with it, memory retention, suggested the Berkeley researchers.
In the meantime, it's not a bad reason to try and get more ZZs.