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Sleep Deprivation Affects Distinct Cognitive Processes in Different Ways


 

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New findings challenge the prevailing views that executive functioning is especially vulnerable to sleep loss and that impairment due to sleep deprivation is generic to cognitive processes subserved by attention.

What goes on in your brain when you’re sleep deprived, and how does it affect your ability to process information and make decisions? A study regarding the effects of sleep deprivation on executive functioning has yielded results that may cause a shift in the current thinking on this topic.

As published in the January issue of Sleep, researchers found that sleep deprivation affects distinct cognitive processes in different ways. Investigators found that working memory was essentially unaffected by as much as 51 hours of total sleep deprivation. Instead, they observed a degradation of nonexecutive components of cognition, such as information intake, that accounted for the overall impairment in subjects’ performance on cognitive tasks. In other words, the sleep-deprived brain appears to be capable of processing information, but this information may be distorted before it can be processed.

These results challenge an existing theory that states that sleep deprivation affects executive functioning more than nonexecutive cognitive processes. They also show that previous experimental support for this theory was hampered by task impurity, the problem that any cognitive performance task involves a number of intertwined cognitive processes that must be distinguished to really understand the effects of sleep deprivation on cognitive performance.

“These findings are significant for our understanding of how sleep deprivation affects the brain,” said principal investigator Hans Van Dongen, PhD, Research Professor at the Washington State University Sleep and Performance Research Center in Spokane. “They show that a large body of research on the effects of sleep deprivation needs to be revisited to verify the conclusions, which may have been drawn incorrectly because of task impurity issues.”

Measuring the Impact of Sleep Loss on Executive Functioning
The study included 23 subjects who spent 6.5 consecutive days in a controlled laboratory environment. One group was kept awake for two consecutive nights (62 hours), while the other was on a normal sleep schedule. Three times throughout the experiment, the subjects completed an executive function task battery composed of tasks that allow for important executive functioning to be examined separately from nonexecutive components of cognition. The task battery measured such executive functions as working memory scanning efficiency, resistance to proactive interference, and aspects of verbal fluency.

Dr. Van Dongen and his colleagues first developed their new perspective following earlier studies that examined individual differences in the effects of sleep deprivation, which showed that these differences depended on the task being performed.

“This suggested that sleep deprivation can affect multiple facets of cognitive task performance in different ways, and that we should look at separate components of cognition and not just overall task performance,” according to Dr. Van Dongen.

Their current study was the first step in a new line of research that the investigators are pursuing, in which they will seek to analyze the effects of sleep deprivation on a variety of distinct cognitive processes. They are planning follow-up studies that will examine how distinct components of decision making are affected by sleep deprivation and how this influences the overall decisions that people make.

Ultimately, this may lead to the development of interventions that target the components of cognition most affected by sleep deprivation. Such interventions could improve decision making in situations in which getting more sleep is not an option. This work will have important implications for emergency responders, police officers, military personnel, and anyone required to make sound decisions in safety-critical environments with little opportunity for sleep, noted Dr. Van Dongen.

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