Separate lines of research have demonstrated that rises in cortisol can benefit memory consolidation, as can the occurrence of sleep soon after encoding. For the first time, we demonstrate that pre-learning cortisol interacts with sleep to benefit memory consolidation, particularly for negative arousing items. Resting cortisol levels during encoding were positively correlated with subsequent memory, but only following a period of sleep. There was no such relation following a period of wakefulness. Using eye tracking, we further reveal that for negative stimuli, this facilitative effect may arise because cortisol strengthens the relationship between looking time at encoding and subsequent memory. We suggest that elevated cortisol may "tag" attended information as important to remember at the time of encoding, thus enabling sleep-based processes to optimally consolidate salient information in a selective manner. Neuroimaging data suggest that this optimized consolidation leads to a refinement of the neural processes recruited for successful retrieval of negative stimuli, with the retrieval of items attended in the presence of elevated cortisol and consolidated over a night of sleep associated with activity in the amygdala and vmPFC.

This Short Review critically evaluates three hypotheses about the effects of emotion on memory: First, emotion usually enhances memory. Second, when emotion does not enhance memory, this can be understood by the magnitude of physiological arousal elicited, with arousal benefiting memory to a point but then having a detrimental influence. Third, when emotion facilitates the processing of information, this also facilitates the retention of that same information. For each of these hypotheses, we summarize the evidence consistent with it, present counter-evidence suggesting boundary conditions for the effect, and discuss the implications for future research.

Hypervigilance toward ambiguous or threatening stimuli is a prominent feature in many trauma survivors including active and returning soldiers. This study set out to investigate the factors that contribute to hypervigilance in a mixed sample. One hundred and forty-five individuals, 50 of whom were war zone veterans, filled out a series of questionnaires including the Hypervigilance Questionnaire (HVQ; Kimble, Fleming, & Bennion, 2009). Other participants included military cadets, college undergraduates, and a traumatized community sample. In this sample, a history of military deployment and posttraumatic stress disorder symptoms independently predicted hypervigilance. The findings suggest that deployment to a war zone, in and of itself, can lead to hypervigilant behavior. Therefore, characterizing hypervigilance as pathological in a veteran sample must be done so with caution.

Although both nonscientists and scientists alike have long promoted the idea that sleep is beneficial to memory, recent work has shown that the effects of sleep on memory are selective: Sleep ‘selects,’ or preferentially consolidates, the most salient or goal-relevant aspect of an experience, resulting in facilitated retrieval of that information upon waking. In this review, we focus on the selective effects of sleep on emotional memory, highlighting 3 potential mechanisms responsible for these effects. We first discuss how the ‘replaying’ of information during consolidation leads to enhanced memory, with emotionally salient information being preferentially reactivated during sleep. We then discuss how the neurobiology of sleep—specifically, theta oscillations that may enable prefrontal-limbic connections and changing acetylcholine levels—may support the selective consolidation of emotional experiences. Lastly, we provide evidence that information that is preferentially consolidated during sleep may be initially selected during encoding, with endogenous cortisol ‘tagging’ a salient event as important to remember, thus leading to its prioritized consolidation during sleep. In addition to discussing the selective effects of sleep on emotional memory and the potential mechanisms underlying these effects, we emphasize the critical implications of this research for educational and vocational settings.

Prior research has demonstrated that sleep enhances memory for future-relevant information, including memory for information that is salient due to emotion, reward, or knowledge of a later memory test. Although sleep has been shown to prioritize information with any of these characteristics, the present study investigates the novel question of how sleep prioritizes information when multiple salience cues exist. Participants encoded scenes that were future-relevant based on emotion (emotional vs. neutral), reward (rewarded vs. unrewarded), and instructed learning (intentionally vs. incidentally encoded), preceding a delay consisting of a nap, an equivalent time period spent awake, or a nap followed by wakefulness (to control for effects of interference). Recognition testing revealed that when multiple dimensions of future relevance co-occur, sleep prioritizes top-down, goal-directed cues (instructed learning, and to a lesser degree, reward) over bottom-up, stimulus-driven characteristics (emotion). Further, results showed that these factors interact; the effect of a nap on intentionally encoded information was especially strong for neutral (relative to emotional) information, suggesting that once one cue for future relevance is present, there are diminishing returns with additional cues. Sleep may binarize information based on whether it is future-relevant or not, preferentially consolidating memory for the former category. Potential neural mechanisms underlying these selective effects and the implications of this research for educational and vocational domains are discussed. (PsycINFO Database Record