Author Interviews, Psychological Science, Sleep Disorders / 01.05.2015
Poor Sleep Quality Increases Mood Disturbances
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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