MedicalResearch.com Interview with:
Jaime L. Tartar PhD
Behavioral Neuroscience Major Chair
Division of Social and Behavioral Sciences
Nova Southeastern University
Fort Lauderdale, Florida
Medical Research: What is the background for this study? What are the main findings?
Dr. Tartar: We set out to understand how poor sleep quality can influence emotion processing. Our rationale for this study was that although sleep perturbations are known to impair cognitive performance, it is not currently clear how poor sleep alters emotion processes. However, given that poor sleep quality is closely associated with the development of mood disorders, it is important to understand how sleep quality affects emotional functioning. We specifically examined the possibility that poor sleep quality creates a cognitive bias in memory and interpretation for emotionally negative stimuli. This would result in maladaptive emotional experiences- for example, through enhanced memory for emotionally negative events (which is also a common characteristic of depression). The idea that negative cognitive bias occurs with poor sleep quality is also consistent with the finding that sleep loss increases sensitivity to emotional stimuli as well as increases undesirable mood states like irritability, anger, and hostility. It is particularly noteworthy that sleep perturbations result in
increased emotionality since sleep perturbations are shown to result in a
decrease in non-emotional cognitive processes (attention and memory). In order to clarify the role of sleep quality on emotion processing, we tested the relationship between sleep quality and a negative cognitive bias through the use of an emotional memory task. We also aimed to contrast these findings with performance on a non-emotional attention task since sleep impairments have previously been shown to cause impairments in (non-emotional) sustained attention. An interesting feature of the study was that we also accounted for potential confounding effects of stress sensitivity and chronotype (ones preferred time of day) since these are both factors known to be related to sleep quality. We found that, compared to those who reported good subjective sleep quality, participants who reported poor subjective
sleep quality showed a negative cognitive bias towards emotionally negative stimuli. Also in agreement with previous work, we show that poor sleep quality has a negative effect on affective symptom measures- poor sleep quality relates to increased depressive symptoms, greater state and trait anxiety, and higher total mood disturbance (increased tension, fatigue, confusion and less vigor). Consistent with previous findings, we also found that subjective sleep quality was related to a decrease in performance on a sustained attention task. Although previous research suggests that stress sensitivity and chronotype would be important variables to consider in the impact of sleep perturbations on emotion processing, we did not find any stress, chronotype, or time of testing effects on these measures.
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MedicalResearch.com Interview with:
Hans P.A. Van Dongen, Ph.D.
Director, Sleep and Performance Research Center
Research Professor, College of Medical Sciences
Washington State University Spokane, Spokane, WA
On behalf of the authors: Paul Whitney PhD, John Hinson PhD, Melinda Jackson PhD, Hans Van Dongen PhD
MedicalResearch: What is the background for this study? What are the main findings?
Research: Our main interest is in better understanding why people sometimes are able to manage perfectly well with sleep loss, while at other times sleep loss can have profoundly negative effects. We found that sleep deprivation reduces the effectiveness of signals used to tell when you are right or wrong, an effect we labeled feedback blunting.
Subjects in the study performed a decision making task that was simple but required feedback, i.e., a signal indicating the response was correct or incorrect, to perform correctly. We found that people who were sleep deprived were no longer able to use the feedback information to make correct responses. And when people had to adapt to unexpected changes in when to respond, sleep deprived people were completely unable to adapt to these changing circumstances.
The finding of feedback blunting in this study indicates that people who are sleep deprived not only have trouble sustaining attention to details in the environment (a well established effect of sleep loss), they also have trouble changing the focus of attention to deal with changing circumstances.
An interesting paradox in the research literature has been that people have been shown in many circumstances to perform complex tasks at a very high level while sleep deprived. Yet, we know from real-world experience that sleep deprived people can make catastrophic, life-threatening decisions that they would never have made if they were well rested. The current study is the first to shed light on this issue. It showed that sleep deprived people who get feedback, telling them that their actions are not effective, are less capable of changing their behavior.
The study is part of a line of research in which we are trying to identify how sleep loss changes specific components of cognition, and how these changes may lead to serious problems in everyday life activities. Being able to study and understand these effects of sleep deprivation under controlled conditions is an important step toward preventing human error under real world conditions.
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