Study: Losing sleep can hurt your memory

A study shows that losing sleep can hurt a person's memory.

Lack of sleep, already considered a public health epidemic, can also lead to errors in memory, finds a new study by researchers at Michigan State University and the University of California, Irvine.

The study, published online in the journalPsychological Science, found participants deprived of a night's sleep were more likely to flub the details of a simulated burglary they were shown in a series of images.

Distorted memory can have serious consequences in areas such as criminal justice, where eyewitness misidentifications are thought to be the leading cause of wrongful convictions in the United States.

"We found memory distortion is greater after sleep deprivation," said Kimberly Fenn, MSU associate professor of psychology and co-investigator on the study. "And people are getting less sleep each night than they ever have."

The Centers for Disease Control and Prevention calls insufficient sleep an epidemic and said it's linked to vehicle crashes, industrial disasters and chronic diseases such as hypertension and diabetes.

The researchers conducted experiments at MSU and UC-Irvine to gauge the effect of insufficient sleep on memory. The results: Participants who were kept awake for 24 hours -- and even those who got five or fewer hours of sleep -- were more likely to mix up event details than participants who were well rested.

"People who repeatedly get low amounts of sleep every night could be more prone in the long run to develop these forms of memory distortion," Fenn said. "It's not just a full night of sleep deprivation that puts them at risk."

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Brain damage can occur even in mild brain injuries

A study shows that even a mild brain injury can cause lasting brain damage.

Even mild traumatic brain injury may cause brain damage and thinking and memory problems, according to a study published in the July 16, 2014, online issue of Neurology®, the medical journal of the American Academy of Neurology.

For the study, 44 people with a mild traumatic brain injury and nine people with a moderate traumatic brain injury were compared to 33 people with no brain injury. All of the participants took tests of their thinking and memory skills. At the same time, they had diffusion tensor imaging scans, a type of MRI scan that is more sensitive than traditional MRI for detecting damage to brain cells and helps map fiber tracts that connect brain regions. The people with brain injuries had their scans an average of six days after the injury. A year later, 23 of those with injuries had another scan and took the cognitive tests again.

Compared to the people with no brain injury, those with injuries had brain damage in brain white matter consisting of disruption to nerve axons, those parts of nerve cells that make up white matter and that allow brain cells to transmit messages to each other.

The study found that patient scores on the verbal letter fluency task, a test of thinking and memory skills, were 25 percent lower than in the healthy people. This was strongly related to the imaging measures of white matter damage.

“Most of the studies thus far have focused on people with severe and chronic traumatic brain injury,” said study author Andrew Blamire, PhD, of Newcastle University in the United Kingdom. “We studied patients who had suffered clinically mild injuries often from common accidents such as falling from a bicycle, or slow speed car accidents. This finding is especially important, as 90 percent of all traumatic brain injuries are mild to moderate.”

One year after the injury, the scores on thinking and memory tests were the same for people with brain injuries and those with no injuries, but there were still areas of brain damage in people with injuries. “These results show that thinking skills were recovering over time,” Blamire said. “The areas of brain damage were not as widespread across the brain as previously, but focused in certain areas of the brain, which could indicate that the brain was compensating for the injuries.”

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