It is by now well established that sleep can be an important tool when it comes to enhancing memory and learning skills. And now, a new study sheds light on the role that dreams play in this important process.
Led by scientists at Beth Israel Deaconess Medical Center (BIDMC), the new findings suggest that dreams may be the sleeping brain’s way of telling us that it is hard at work on the process of memory consolidation, integrating our recent experiences to help us with performance-related tasks in the short run and, in the long run, translating this material into information that will have widespread application to our lives. The study is reported in the April 22 On-line issue of Current Biology.
“What’s got us really excited, is that after nearly 100 years of debate about the function of dreams, this study tells us that dreams are the brain’s way of processing, integrating and really understanding new information,” explains senior author Robert Stickgold, PhD, Director of the Center for Sleep and Cognition at BIDMC and Associate Professor of Psychiatry at Harvard Medical School. “Dreams are a clear indication that the sleeping brain is working on memories at multiple levels, including ways that will directly improve performance.”
At the outset, the authors hypothesized that dreaming about a learning experience during nonrapid eye movement (NREM) sleep would lead to improved performance on a hippocampus-dependent spatial memory task. (The hippocampus is a region of the brain responsible for storing spatial memory.)
To test this hypothesis, the investigators had 99 subjects spend an hour training on a “virtual maze task,” a computer exercise in which they were asked to navigate through and learn the layout of a complex 3D maze with the goal of reaching an endpoint as quickly as possible. Following this initial training, participants were assigned to either take a 90-minute nap or to engage in quiet activities but remain awake. At various times, subjects were also asked to describe what was going through their minds, or in the case of the nappers, what they had been dreaming about. Five hours after the initial exercise, the subjects were retested on the maze task.
The results were striking.
The non-nappers showed no signs of improvement on the second test – even if they had reported thinking about the maze during their rest period. Similarly, the subjects who napped, but who did not report experiencing any maze-related dreams or thoughts during their sleep period, showed little, if any, improvement. But, the nappers who described dreaming about the task showed dramatic improvement, 10 times more than that shown by those nappers who reported having no maze-related dreams.
“These dreamers described various scenarios – seeing people at checkpoints in a maze, being lost in a bat cave, or even just hearing the background music from the computer game,” explains first author Erin Wamsley, PhD, a postdoctoral fellow at BIDMC and Harvard Medical School. These interpretations suggest that not only was sleep necessary to “consolidate” the information, but that the dreams were an outward reflection that the brain had been busy at work on this very task.
Of particular note, say the authors, the subjects who performed better were not more interested or motivated than the other subjects. But, they say, there was one distinct difference that was noted.
“The subjects who dreamed about the maze had done relatively poorly during training,” explains Wamsley. “Our findings suggest that if something is difficult for you, it’s more meaningful to you and the sleeping brain therefore focuses on that subject – it ‘knows’ you need to work on it to get better, and this seems to be where dreaming can be of most benefit.”
Furthermore, this memory processing was dependent on being in a sleeping state. Even when a waking subject “rehearsed and reviewed” the path of the maze in his mind, if he did not sleep, then he did not see any improvement, suggesting that there is something unique about the brain’s physiology during sleep that permits this memory processing.
“In fact,” says Stickgold, “this may be one of the main goals that led to the evolution of sleep. If you remain awake [following the test] you perform worse on the subsequent task. Your memory actually decays, no matter how much you might think about the maze.
“We’re not saying that when you learn something it is dreaming that causes you to remember it,” he adds. “Rather, it appears that when you have a new experience it sets in motion a series of parallel events that allow the brain to consolidate and process memories.”
Ultimately, say the authors, the sleeping brain seems to be accomplishing two separate functions: While the hippocampus is processing information that is readily understandable (i.e. navigating the maze), at the same time, the brain’s higher cortical areas are applying this information to an issue that is more complex and less concrete (i.e. how to navigate through a maze of job application forms).
“Our [nonconscious] brain works on the things that it deems are most important,” adds Wamsley. “Every day, we are gathering and encountering tremendous amounts of information and new experiences,” she adds. “It would seem that our dreams are asking the question, ‘How do I use this information to inform my life?’”
Study coauthors include BIDMC investigators Matthew Tucker, Joseph Benavides and Jessica Payne (currently of the University of Notre Dame).
This study was supported by grants from the National Institutes of Health.
BIDMC is a patient care, teaching and research affiliate of Harvard Medical School, and consistently ranks in the top four in National Institutes of Health funding among independent hospitals nationwide. BIDMC is a clinical partner of the Joslin Diabetes Center and a research partner of the Dana-Farber/Harvard Cancer Center. BIDMC is the official hospital of the Boston Red Sox.
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Watch What They’re Watching:Children Viewing Adult-targeted TV May Become Sexually Active Earlier In Life
Early onset of sexual activity among teens may relate to the amount of adult content children were exposed to during their childhood, according to a new study released by Children’s Hospital Boston. Based on a longitudinal study tracking children from age six to eighteen, researchers found that the younger children are exposed to content intended for adults in television and movies, the earlier they become sexually active during adolescence. The findings are being presented at the Pediatric Academic Societies meetings on Monday, May 4 in Baltimore.
“Television and movies are among the leading sources of information about sex and relationships for adolescents,” says Hernan Delgado, MD, fellow in the Division of Adolescent/Young Adult Medicine at Children’s Hospital Boston and lead author of the study. “Our research shows that their sexual attitudes and expectations are influenced much earlier in life.”
The study consisted of 754 participants, 365 males and 389 females, who were tracked during two stages in life: first during childhood, and again five years later when their ages ranged from 12 to 18-years-old. At each stage, the television programs and movies viewed, and the amount of time spent watching them over a sample weekday and weekend day were logged. The program titles were used to determine what content was intended for adults. The participants’ onset of sexual activity was then tracked during the second stage.
According to the findings, when the youngest children in the sample–ages 6 to 8-years-old–were exposed to adult-targeted television and movies, they were more likely to have sex earlier when compared those who watched less adult-targeted content. The study found that for every hour the youngest group of children watched adult-targeted content over the two sample days, their chances of having sex during early adolescence increased by 33 percent. Meanwhile, the reverse was not found to be true that is, becoming sexually active in adolescence did not subsequently increase youth’s viewing of adult-targeted television and movies.
“Adult entertainment often deals with issues and challenges that adults face, including the complexities of sexual relationships. Children have neither the life experience nor the brain development to fully differentiate between a reality they are moving toward and a fiction meant solely to entertain,” adds David Bickham, PhD, staff scientist in the Center on Media and Child Health and co-author of the study. “Children learn from media, and when they watch media with sexual references and innuendos, our research suggests they are more likely to engage in sexual activity earlier in life.”
The researchers encourage parents to follow current American Academy of Pediatrics viewing guidelines such as no television in the bedroom, no more than 1 to 2 hours of screen time a day, and to co-view television programs and have an open dialogue about its content with your children. They also suggest that–while the results demonstrate a longitudinal relationship–more research needs be done to understand how media influences children’s growing awareness of human relationships and sexual behavior.
“Adolescent sexual behaviors may be influenced at a younger age, but this is just one area we studied,” adds Dr. Delgado. “We showed how adult media impacts children into adolescence, yet there are a number of other themes in adult television shows and movies, like violence and language, whose influence also needs to be tracked from childhood to adolescence.”
The study was funded by support by grants from the Maternal and Child Health Bureau and the Center on Media and Child Health.
Children’s Hospital Boston is home to the world’s largest research enterprise based at a pediatric medical center, where its discoveries have benefited both children and adults since 1869. More than 500 scientists, including eight members of the National Academy of Sciences, 11 members of the Institute of Medicine and 13 members of the Howard Hughes Medical Institute comprise Children’s research community. Founded as a 20-bed hospital for children, Children’s Hospital Boston today is a 397-bed comprehensive center for pediatric and adolescent health care grounded in the values of excellence in patient care and sensitivity to the complex needs and diversity of children and families. Children’s also is the primary pediatric teaching affiliate of Harvard Medical School.Source: MedicalNewsToday.com, Children’s Hospital Boston