napping

Day-time naps help us acquire information not consciously perceived

'I'll sleep on it' proves scientifically sound advice

October 4, 2018

Science Daily/University of Bristol

The age-old adage 'I'll sleep on it' has proven to be scientifically sound advice, according to a new study which measured changes in people's brain activity and responses before and after a nap. The findings support the advice which suggests that a period of sleep may help weighing up pros and cons or gain insight before making a challenging decision.

 

The Medical Research Council-funded study, led by University of Bristol researchers, aimed to understand whether a short period of sleep can help us process unconscious information and how this might affect behaviour and reaction time.

 

The findings further reveal the benefits of a short bout of sleep on cognitive brain function and found that even during short bouts of sleep we process information that we are not consciously aware of.

 

While previous evidence demonstrates that sleep helps problem solving, resulting in enhanced cognition upon awaking; it was not clear whether some form of conscious mental process was required before or during sleep to aid problem solving. In this study, researchers hid information by presenting it very briefly and "masking" it -- so it was never consciously perceived -- the masked prime task. The hidden information, however, was processed at a subliminal level within the brain and the extent to which it interferes with responses to consciously perceived information was measured.

 

Sixteen healthy participants across a range of ages were recruited to take part in an experiment. Participants carried out two tasks -- the masked prime task and a control task where participants simply responded when they saw a red or blue square on a screen. Participants practiced the tasks and then either stayed awake or took a 90-minute nap before doing the tasks again.

 

Using an EEG, which records the electrical activity naturally produced in the brain, researchers measured the change in brain activity and response pre-and-post nap.

 

Sleep (but not wake) improved processing speed in the masked prime task -- but not in the control task -- suggesting sleep-specific improvements in processing of subconsciously presented primes.

 

The findings suggest that even a short bout of sleep may help improve our responses and process information. Therefore, the results here suggest a potentially sleep-dependent, task-specific enhancement of brain processing that could optimise human goal-directed behaviour.

 

Importantly, while it is already known that the process of acquiring knowledge and information recall, memory, is strengthened during sleep. This study suggests that information acquired during wakefulness may potentially be processed in some deeper, qualitative way during sleep

 

Dr LizCoulthard, Consultant Senior Lecturer in Dementia Neurology at the University of Bristol Medical School: Translational Health Sciences, said: "The findings are remarkable in that they can occur in the absence of initial intentional, conscious awareness, by processing of implicitly presented cues beneath participants' conscious awareness.

 

"Further research in a larger sample size is needed to compare if and how the findings differ between ages, and investigation of underlying neural mechanisms."

https://www.sciencedaily.com/releases/2018/10/181004095929.htm

To Learn Better, Take a Nap (and Don't Forget to Dream)

April 26, 2010

Science Daily/Beth Israel Deaconess Medical Center

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."

 

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?'"

http://www.sciencedaily.com/releases/2010/04/100422153753.htm

Taking hour-long afternoon naps improves thinking and memory in older Chinese adults

January 5, 2017

American Geriatrics Society

Study participants who took an hour-long nap after lunch did better on the mental tests compared to the people who did not nap. Those who napped for about an hour also did better than people who took shorter or longer rests. People who took no naps, short naps, or longer naps experienced decreases in their mental ability that were about four to six times greater than people who took hour-long naps.

 

Preserving your memory, as well as your ability to think clearly and make decisions, is a key goal for people as they age. Researchers have a growing interest in the role sleep plays in helping older adults maintain their healthy mental function.

 

Recently, researchers examined information provided by nearly 3,000 Chinese adults aged 65 and older to learn whether taking an afternoon nap had any effect on mental health. Their study was published in the Journal of the American Geriatrics Society.

 

Nearly 60 percent of the people in the study said they napped after lunch in the afternoon. They napped between about 30 minutes to more than 90 minutes, with most people taking naps lasting about 63 minutes.

 

The participants took several tests to assess their mental status. They answered simple questions -- such as questions about the date, the season of the year, etc. -- and they did some basic math problems. Participants also were asked to memorize and recall words, and were asked to copy drawings of simple geometric figures. Finally, these older Chinese adults were asked questions about their napping and nighttime sleep habits.

 

According to the study's results, people who took an hour-long nap after lunch did better on the mental tests compared to the people who did not nap. Those who napped for about an hour also did better than people who took shorter or longer rests. People who took no naps, short naps, or longer naps experienced decreases in their mental ability that were about four-to-six times greater than people who took hour-long naps.

 

The people who did not nap, and those who took shorter or longer naps, experienced about the same decline in their mental abilities that a five-year increase in age would be expected to cause.

 

This summary is from "Afternoon Napping and Cognition in Chinese Older Adults: Findings From the China Health and Retirement Longitudinal Study (CHARLS) Baseline Assessment." It appears online ahead of print in the January 2017 issue of the Journal of the American Geriatrics Society. The study authors are Junxin Li, PhD; Pamela Z. Cacchione, PhD; Nancy Hodgson, PhD; Barbara Riegel, PhD; Brendan T. Keenan, MS; Mathew T. Scharf, MD, PhD; Kathy C. Richards, PhD; and Nalaka S. Gooneratne, MD.

https://www.sciencedaily.com/releases/2017/01/170105123148.htm

Sleep Researchers Study Value of Preschool Naps

September 14, 2012

Science Daily/University of Massachusetts Amherst

Parents may feel it's clear that missing a nap means their young children will be grumpy and out-of-sorts, but scientists who study sleep say almost nothing is known about how daytime sleep affects children's coping skills and learning.

 

Now neuroscientist Rebecca Spencer at the University of Massachusetts Amherst has received a five-year, $2 million grant from NIH's Heart, Lung and Blood Institute to significantly advance knowledge about how napping and sleep affect memory, behavior and emotions in preschoolers.

 

"Right now, there's nothing to support teachers who feel that naps can really help young children, there's no concrete science behind that," the neuroscientist says. "But if sleep is going to enhance all these benefits of attending preschool, we need to know it."

 

Over the next five years, Spencer and her graduate students hope to study about 480 preschoolers between 3 and 5 years old, boys and girls in diverse communities across western Massachusetts. The research will include fact-based and emotional memory studies with and without napping, measures of physical activity levels and parent reports of their children's' nighttime sleep, to find out how classroom experience interacts with sleep and physical activity and whether daytime sleep enhances learning. The research will also explore the relationship between sleep and behavior disorders.

 

"I think we'll have a rich data set for examining sleep, physical activity and the child's behavior," says Spencer. "We think that the nap benefit is going to be especially useful for kids who don't get optimal overnight sleep. Culture plays a role in how late you stay up, and some kids live in noisy inner city neighborhoods. If we can help them with a nap, we want to know that."

http://www.sciencedaily.com/releases/2012/09/120914123808.htm

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