The Longer You’re Awake, the Slower You Get

ScienceDaily (July 27, 2012) — Anyone that has ever had trouble sleeping can attest to the difficulties at work the following day. Experts recommend eight hours of sleep per night for ideal health and productivity, but what if five to six hours of sleep is your norm? Is your work still negatively affected? A team of researchers at Brigham and Women’s Hospital (BWH) have discovered that regardless of how tired you perceive yourself to be, that lack of sleep can influence the way you perform certain tasks.


 

This finding is published in the July 26, 2012 online edition of The Journal of Vision.

“Our team decided to look at how sleep might affect complex visual search tasks, because they are common in safety-sensitive activities, such as air-traffic control, baggage screening, and monitoring power plant operations,” explained Jeanne F. Duffy, PhD, MBA, senior author on this study and associate neuroscientist at BWH. “These types of jobs involve processes that require repeated, quick memory encoding and retrieval of visual information, in combination with decision making about the information.”

Researchers collected and analyzed data from visual search tasks from 12 participants over a one month study. In the first week, all participants were scheduled to sleep 10-12 hours per night to make sure they were well-rested. For the following three weeks, the participants were scheduled to sleep the equivalent of 5.6 hours per night, and also had their sleep times scheduled on a 28-hour cycle, mirroring chronic jet lag. The research team gave the participants computer tests that involved visual search tasks and recorded how quickly the participants could find important information, and also how accurate they were in identifying it. The researchers report that the longer the participants were awake, the more slowly they identified the important information in the test. Additionally, during the biological night time, 12 a.m. -6 a.m., participants (who were unaware of the time throughout the study) also performed the tasks more slowly than they did during the daytime.

“This research provides valuable information for workers, and their employers, who perform these types of visual search tasks during the night shift, because they will do it much more slowly than when they are working during the day,” said Duffy. “The longer someone is awake, the more the ability to perform a task, in this case a visual search, is hindered, and this impact of being awake is even stronger at night.”

While the accuracy of the participants stayed the fairly constant, they were slower to identify the relevant information as the weeks went on. The self-ratings of sleepiness only got slightly worse during the second and third weeks on the study schedule, yet the data show that they were performing the visual search tasks significantly slower than in the first week. This finding suggests that someone’s perceptions of how tired they are do not always match their performance ability, explains Duffy.

This research was supported by NIH grant P01 AG09975 and was conducted in the BWH CCI, part of the Harvard Catalyst Clinical and Translational Science Center (UL1 RR025758-01), formerly a GCRC (M01RR02635). Development and implementation of the visual search task was supported in part by NIH grant R21 AT002571. JFD was supported in part by the BWHBRI Fund to Sustain Research Excellence; MM was supported by fellowships from the La-Roche and Novartis Foundations (Switzerland) and Jazz Pharmaceuticals (USA); SWC was supported in part by a fellowship from the Natural Sciences and Engineering Research Council of Canada.

 

Link:

http://www.brighamandwomens.org/about_bwh/publicaffairs/news/pressreleases/PressRelease.aspx?sub=0&PageID=1231

Journal Reference:

  1. Marc Pomplun,    Edward J. Silva,    Joseph M. Ronda,    Sean W. Cain,    Mirjam Y. Münch,    Charles A. Czeisler,    and Jeanne F. Duffy. The effects of circadian phase, time awake, and imposed sleep restriction on performing complex visual tasks: Evidence from comparative visual search. The Journal of Vision, July 26, 2012 DOI: 10.1167/12.7.14

Citation:

Brigham and Women’s Hospital (2012, July 27). The longer you’re awake, the slower you get. ScienceDaily. Retrieved July 29, 2012, from http://www.sciencedaily.com­ /releases/2012/07/120727111317.htm

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Lucid Dreamers Help Scientists Locate the Seat of Meta-Consciousness in the Brain

ScienceDaily (July 27, 2012) — Studies of lucid dreamers show which centers of the brain become active when we become aware of ourselves in dreams.


Which areas of the brain help us to perceive our world in a self-reflective manner is difficult to measure. During wakefulness, we are always conscious of ourselves. In sleep, however, we are not. But there are people, known as lucid dreamers, who can become aware of dreaming during sleep. Studies employing magnetic resonance tomography (MRT) have now been able to demonstrate that a specific cortical network consisting of the right dorsolateral prefrontal cortex, the frontopolar regions and the precuneus is activated when this lucid consciousness is attained. All of these regions are associated with self-reflective functions. This research into lucid dreaming gives the authors of the latest study insight into the neural basis of human consciousness.

The human capacity of self-perception, self-reflection and consciousness development are among the unsolved mysteries of neuroscience. Despite modern imaging techniques, it is still impossible to fully visualize what goes on in the brain when people move to consciousness from an unconscious state. The problem lies in the fact that it is difficult to watch our brain during this transitional change. Although this process is the same, every time a person awakens from sleep, the basic activity of our brain is usually greatly reduced during deep sleep. This makes it impossible to clearly delineate the specific brain activity underlying the regained self-perception and consciousness during the transition to wakefulness from the global changes in brain activity that takes place at the same time.

Scientists from the Max Planck Institutes of Psychiatry in Munich and for Human Cognitive and Brain Sciences in Leipzig and from Charité in Berlin have now studied people who are aware that they are dreaming while being in a dream state, and are also able to deliberately control their dreams. Those so-called lucid dreamers have access to their memories during lucid dreaming, can perform actions and are aware of themselves – although remaining unmistakably in a dream state and not waking up. As author Martin Dresler explains, “In a normal dream, we have a very basal consciousness, we experience perceptions and emotions but we are not aware that we are only dreaming. It’s only in a lucid dream that the dreamer gets a meta-insight into his or her state.”

By comparing the activity of the brain during one of these lucid periods with the activity measured immediately before in a normal dream, the scientists were able to identify the characteristic brain activities of lucid awareness.

“The general basic activity of the brain is similar in a normal dream and in a lucid dream,” says Michael Czisch, head of a research group at the Max Planck Institute of Psychiatry. “In a lucid state, however, the activity in certain areas of the cerebral cortex increases markedly within seconds. The involved areas of the cerebral cortex are the right dorsolateral prefrontal cortex, to which commonly the function of self-assessment is attributed, and the frontopolar regions, which are responsible for evaluating our own thoughts and feelings. The precuneus is also especially active, a part of the brain that has long been linked with self-perception.” The findings confirm earlier studies and have made the neural networks of a conscious mental state visible for the first time.

 

Link:

http://www.mpg.de/5925490/meta-consciousness-brain

Journal Reference:

  1. Martin Dresler, Renate Wehrle, Victor I. Spoormaker, Stefan P. Koch, Florian Holsboer, Axel Steiger, Hellmuth Obrig, Philipp G. Sämann, Michael Czisch. Neural Correlates of Dream Lucidity Obtained from Contrasting Lucid versus Non-Lucid REM Sleep: A Combined EEG/fMRI Case Study. Sleep, 2012;35(7):1017-1020

Citation:

Max-Planck-Gesellschaft (2012, July 27). Lucid dreamers help scientists locate the seat of meta-consciousness in the brain. ScienceDaily. Retrieved July 29, 2012, from http://www.sciencedaily.com­ /releases/2012/07/120727095555.htm

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