Journey into the night: unveiling the impact of sleep deprivation on mood and emotional processing
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Abstract
INTRODUCTION: Previous literature has demonstrated the imperative role of sleep in regulating various cognitive and emotional functions such as mood regulation and memory processing. Total sleep deprivation (SD) has been overwhelmingly shown to decrease positive affect (PA) and, less consistently, alter negative affect (NA) as well. In addition, SD has been shown to negatively impact overall memory, and may have differential impacts on neutral vs emotional memory content. This study aims to further clarify the effects of SD on mood and investigate if SD has similar or different impacts on emotional and neutral memory content. If SD impacts both mood and emotional memory processing, the exploratory aim of this research is to determine the relationship between mood and emotional memory processing following SD.
METHODS: Sixty-nine participants were assigned to the sleep group (n = 21) and SD group (n = 48) as part of a larger investigation, where the SD group was further stratified for subsequent analyses. Participants completed the Positive and Negative Affect Scores (PANAS) assessment in the evening. Sleep group participants went home for the night to sleep and returned to the hospital in the morning, whereas SD group participants remained awake in the hospital overnight. In the morning, participants completed the PANAS test again and participants performed both the encoding and recognition portions of the Emotional Trade-Off (ETO) task to investigate differential effects on neutral and negative memory content. Repeated measures analysis of variance (ANOVA) was used to analyze PANAS and ETO scores with a significant threshold of p <0.05.
RESULTS: No baseline (session 1) differences in PA and NA were found between the sleep and SD groups. At session 2 (morning), the SD group had significantly lower PA scores compared to the sleep group. Additionally, a significant decrease in PA in the SD group from evening to morning was observed, while NA remained stable. A significant condition effect on memory was also found, with the SD group performing worse on overall memory compared to the sleep group. A significant valence x scene component interaction was also found, and the emotional trade-off effect was successfully replicated in both rested and sleep-deprived conditions. Finally, a positive association was observed between PA and background scene components from the ETO.
DISCUSSION: While NA did not change significantly from morning to evening testing sessions, PA was found to decrease significantly for the SD group. SD participants in this study exhibited significantly worse overall memory compared to those who slept, and all participants replicated the emotional trade-off effect. Exploratory analysis found a correlation between higher PA scores and better recollection of backgrounds, potentially explained by the broaden-and-build theory that suggests positive emotions enhance observance and memory formation. Future research should build upon these findings and further investigate the interaction between mood and emotional memory and their relationship with different features of sleep.
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2024