Browsing by Author "Lipinska, Malgorzata"

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    Open Access
    Associations between sleep and cognitive-affective functioning in Posttraumatic Stress Disorder
    (2017) Lipinska, Malgorzata; Thomas, Kevin
    The current research tested the proposition that the sleep disruption characteristic of posttraumatic stress disorder (PTSD) has discrete, predictable, and significant effects on the processing of neutral declarative memory, emotional memory, and emotional reactivity. Research spanning multiple neuroscientific literatures demonstrates that healthy, uninterrupted sleep is critical for memory consolidation and emotional regulation, and that PTSD-diagnosed individuals experience sleep disruption, memory deficits, and emotional dysregulation. To test whether these behavioral, cognitive, and affective characteristics of PTSD are meaningfully related, I recruited three groups of participants: PTSD (n = 21), trauma-exposed non-PTSD (TE; n = 19), and healthy controls (HC; n = 20). Each participant was assessed before and after an 8-hour period of sleep and an 8-hour period of waking activity. The assessment featured measures of neutral declarative memory (learning of stimuli before the delay, and a free recall task afterward), emotional memory (exposure to highly-arousing negatively valenced, highly-arousing positively valenced, and low arousing neutral pictures before the delay, and a recognition task afterward), and emotional reactivity (physiological responses to the emotional pictures, both before and after the delay). The results are presented under the headings of four investigations. Investigation 1, which focused on objective and subjective sleep quality, suggested that PTSD-diagnosed participants had decreased sleep depth in comparison to HC participants, but presented with no other evidence of objective sleep disruption. Furthermore, PTSD-diagnosed participants reported better subjective sleep quality in the sleep laboratory than in their home environment, an effect not observed in TE and HC participants. Investigation 2, which focused on neutral declarative memory, suggested that after a sleep-filled, but not wake-filled, delay, PTSD-diagnosed participants retained less neutral declarative information than TE and HC participants. Furthermore, increased fragmentation of rapid eye movement (REM) sleep in PTSD-diagnosed individuals was a significant predictor of post-sleep memory retention deficits. In contrast, Investigations 3 and 4 suggested no significant between-group differences in emotional memory or emotional reactivity. However, Investigation 3 suggested that, after a sleep-filled delay, pictures of all valence and arousal categories were recognized equally accurately by all participants. In contrast, after a wake-filled delay all participants had higher recognition accuracy for negative pictures. Furthermore, Investigation 4 suggested that a sleep-filled delay attenuated emotional reactivity to pictures of all arousal and valence categories, whereas a wake-filled delay was associated with a rise in emotional reactivity across the day. Together, these results suggest that fairly small sleep disruptions (specific to REM-related changes) in PTSD-diagnosed individuals will affect retention of neutral declarative information, but will have no significant effects on the processing of, or reactivity toward, arousing and valenced stimuli. Overall, these findings allow the conclusion that, in PTSD, the co-occurrence of sleep and neutral declarative memory difficulties is not accidental – that is, these two symptom clusters are meaningfully related. Furthermore, the results demonstrate that a reasonable, not necessarily perfect, night of sleep in PTSD is associated with intact functioning within certain cognitive and affective domains. The research bolsters the neuroscientific view of sleep as a critical biological process linked integrally to psychological well-being.
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    The functional neurophysiological sequelae associated with high frequency dream recallers
    (2018) van Wyk, Mariza; Solms, Mark; Lipinska, Malgorzata
    Background: Dreaming is a universal experience, yet there is considerable inter-individual variability with regard to dream recall frequency (DRF). Research on DRF has been prolific leading to the development of various models delineating possible processes involved in dream recall. One such model is the 'arousal-retrieval' model positing that intra-sleep wakefulness is required for dream traces to be encoded into long-term storage, essentially proposing increased DRF as a product of a better memory for dreams. Results from recent studies support this model by demonstrating longer periods of intra-sleep wakefulness in high frequency recallers (HFRs) compared to low frequency recallers (LFRs). Furthermore, results showed heightened brain reactivity, as well as increased regional cerebral blood flow in areas in the brain associated with dream production. These results are indicative of the existence of a functional neurophysiological trait innate to HRs, while also supporting the premise that apart from a better memory for dreams, HRs also may produce more dreams. Awakenings from rapid eye movement (REM) sleep yield the highest dream recall rates, rendering REM sleep as a reasonable starting point for studying rates of dream production. Furthermore, increased dream production during REM sleep might also affect related processes, for example, leading to enhanced overnight emotional memory consolidation and emotion regulation. Hypotheses: The current study investigated the functional neurophysiological sequelae associated with HFRs in a design where HFRs are compared to LFRs. Hypotheses include: (1) HFRs will score significantly higher on certain personality dimensions; (2) HFRs will experience significantly more awakenings, as well as longer periods of intra-sleep wakefulness; (3) HFRs will have significantly higher rates of dream production as measured by the frequency of eye movements (REM density) during REM sleep; and (4) increased dream production during REM sleep will lead to enhanced overnight emotional memory consolidation and emotion regulation in HFRs. Methods: The study consisted of two groups of healthy young adults: high frequency recallers (n = 19) and low frequency recallers (n = 17) who underwent polysomnographic recordings on two non-consecutive nights. Memory tasks and affective questionnaires were completed before and after a night of sleep. Results: (1) HFRs scored significantly higher on the 'agreeableness' personality dimension and on the Boundary Questionnaire; (2) HFRs experienced significantly more awakenings, especially from stage 2 non-rem (NREM) sleep, as well as significantly longer periods of intra-sleep wakefulness; (3) no significant between-group differences with regard to REM density, nor (4) overnight emotional memory consolidation and emotion regulation were found. Conclusion: Results support, firstly, the proposition that certain personality traits, differences in sleep architecture, and increased DRF are an expression of a functional neurophysiological arrangement innate to HFRs. Secondly, the findings suggest that NREM sleep, as opposed to REM sleep, is important in relation to DRF in this specific population. This is the first study to not only replicate existing findings, but to also contribute to the extant literature by illuminating additional characteristics and features associated with HFRs.
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    Investigating the relationship between sleep and emotion amongst club rugby players
    (2024) Rawoot, Sameenah; Lipinska, Malgorzata; Schrieff Leigh
    In rugby players, both sleep and the ability to regulate emotion are essential to performance and well-being. For example, poor sleep quality is associated with competition losses, and the inability to regulate emotions such as impulsivity and aggression is detrimental during play and could lead to injury. Critically, successful emotion regulation is fostered by healthy sleep and evidence shows that poor sleep quality is associated with poor emotion regulation. Therefore, poor sleep quality in this group of individuals may contribute to emotion dysregulation. Other factors that complicate the relationship between sleep and emotion regulation among rugby players include concussion experience, depression, alcohol use, and drug use, because of their independent influence on both sleep and emotion regulation. The purpose of the current study was therefore to investigate the relationship between sleep quality and emotion regulation ability in rugby players who may or may not have a history of concussion, depression, alcohol use, and/or drug use. The current study included a group of participants who played club rugby (Rugby group; n = 21), and a group of sportsmen who did not play any contact sport (Non-Contact Sport group; n = 21). This online study utilized a survey, which included questions regarding demographics, alcohol and drug use, presence and severity of depressive symptoms, history of concussion, sleep quality, and emotion regulation ability. I used one-tailed t-tests, non-parametric measures, and multiple regression analyses to assess the relationship between sleep quality and emotion regulation ability, while controlling for history of concussion, depressive symptoms, alcohol use, and drug use. Results indicated that the Rugby group displayed significantly poorer sleep quality, specifically with respect to sleep disturbance, than the Non-Contact Sport group, p = .05, d = .516. The Rugby group also reported significantly higher emotion regulation difficulties than the Non-Contact Sport group, p = .006, d = 14.36. The analyses also showed that a history of concussion, group, depressive symptoms, alcohol use, and drug use, did not have a significant effect on emotion regulation, whereas sleep disturbance did. The results indicate that there is a strong negative correlation between sleep quality and emotion regulation in club rugby players. The implications of these results indicate that regardless of group allocation (i.e., participating in contact sport vs non-contact sport), sleep disturbance, is the primary factor in determining emotion regulation ability. The results suggest that whether one participates in contact-sport, or non-contact sport, good sleep quality should be a priority, and interventions should be in place for those who struggle with sleep disturbance in particular. However, the generalizability of these results are limited by the small sample size. Key words: concussion, rugby, sleep quality, emotion regulation
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    The relationship between sleep and memory in PTSD
    (2009) Lipinska, Malgorzata; Thomas, Kevin; Kaminer, Debbie
    Previous research has shown that in normal individuals sleep is critical to the formation of memories. Successful memory consolidation during sleep is contingent on the presence of slowwave sleep (SWS), REM sleep and the successful transition of stages across the night. In PTSD, both sleep and memory processes are disrupted, but no previous study has examined whether these two variables are inter-related. This study aimed at determining whether disrupted sleep was a mechanism underlying declarative memory deficits in PTSD, investigating whether memory consolidation during sleep is disrupted in PTSD diagnosed individuals in comparison with controls.
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    The Relationship Between Affect in Dreams and Emotional Memory Consolidation
    (2023) Du Plessis, Li?tte; Lipinska, Malgorzata
    Research in the field of cognitive neuroscience has focused on the role of sleep in various neurocognitive processes such as memory consolidation, however, an area that has not been fully researched is the role of dreaming in these memory processes. This study aimed to determine the relationship between affect experienced in dreams and emotional memory consolidation. Considering that REM dreams are laden with emotion and that emotion enhances memory, one possibility is that dreaming affect could also play a role in emotional memory consolidation. The hypothesis was that the greater the intensity of affect in a dream, the greater the memory retention will be for emotional information, but not neutral information. 126 healthy participants, aged 18 – 50, were recruited. On the night of the study, the participant viewed a series of pictures from the SA-APS in an online environment. Afterwards, they verbally recalled as many pictures as possible. The following morning, they were asked to recall any dreams and rate the emotional intensity of their dreams. Participants then again verbally recalled all the pictures that they could remember from the previous night. Contrary to the prediction, affect intensity, regardless of valence, did not predict memory consolidation of valenced information. The findings rather showed a general effect of dream affect intensity on overall memory retention. Furthermore, a specific emotion, fear, seemed to drive this general consolidation effect. The secondary analysis revealed that an increase in negative affect in dreams predicted better memory retention of negative information. Increased negative affect may create a need for increased mental processing and, in turn, support better memory consolidation. These findings have implications for psychiatric disorders, such as major depression, which is characterised by negative affect and increased memory sensitivity for negative stimuli. Keywords: affect, dreams, emotional memory consolidation, REM sleep