Abstract
Unwanted memories often enter conscious awareness when individuals confront reminders. People vary widely in their talents at suppressing such memory intrusions; however, the factors that govern suppression ability are poorly understood. We tested the hypothesis that successful memory control requires sleep. Following overnight sleep or total sleep deprivation, participants attempted to suppress intrusions of emotionally negative and neutral scenes when confronted with reminders. The sleep-deprived group experienced significantly more intrusions (unsuccessful suppressions) than the sleep group. Deficient control over intrusive thoughts had consequences: Whereas in rested participants suppression reduced behavioral and psychophysiological indices of negative affect for aversive memories, it had no such salutary effect for sleep-deprived participants. Our findings raise the possibility that sleep deprivation disrupts prefrontal control over medial temporal lobe structures that support memory and emotion. These data point to an important role of sleep disturbance in maintaining and exacerbating psychiatric conditions characterized by persistent, unwanted thoughts.
Highlights
Memories of unpleasant experiences and thoughts can intrude into conscious awareness when reminders to them are confronted
The prefrontal–medial temporal lobe (MTL) networks involved in retrieval suppression (Benoit, Hulbert, Huddleston, & Anderson, 2015; Gagnepain et al, 2017; Levy & Anderson, 2012) are disrupted by sleep loss (Yoo, Gujar, Hu, Jolesz, & Walker, 2007), which suggests that losing sleep may heighten people’s vulnerability to intrusive thoughts (Chee, 2004; Mazur, Pace-Schott, & Hobson, 2002; Thomas et al, 2000, 2003; van Schie & Anderson, 2017; Yoo et al, 2007)
Our findings indicate that sleep deprivation substantially increases people’s vulnerability to unwanted memories intruding into conscious awareness when they confront reminders
Summary
Memories of unpleasant experiences and thoughts can intrude into conscious awareness when reminders to them are confronted. According to the inhibitory deficit hypothesis (Levy & Anderson, 2008), individual differences in regulating intrusive memories originate from variation in underlying inhibition function This hypothesis predicts that conditions that strain inhibitory control will likewise undermine the ability to suppress unwanted thoughts. Suppressing retrieval of aversive scenes reduces people’s emotional response to those scenes later on, as revealed by changes in subjective affect ratings for the suppressed stimuli and the relationship of those changes to prefrontally driven down-regulation of the amygdala during memory intrusions (Gagnepain et al, 2017) This impact of retrieval suppression on perceived emotion (referred to hereafter as affect suppression) suggests that retrieval suppression contributes to affective homeostasis by reducing the negative tone of unpleasant events. We quantified variations in memory control success by using the proportion of no-think trials that triggered any awareness of the associated scene, reflecting a momentary failure of retrieval suppression (i.e., reports of briefly or often; referred to hereafter as intrusions)
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