Auflistung nach Autor:in "Sayk, Clara Anna Luise"

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Variability in biological correlates of nightmares and implications for the development of new treatment options
(2024) Sayk, Clara Anna Luise
are very common in both the general population and individuals with psychiatric disorders. They can cause distress, sleep disturbance and impairment in daily functioning. Several biological correlates of nightmares have been investigated in the last decades, such as brain activity during sleep, changes in heart rate, electrodermal activity or cortisol levels. All of these measures indicate some form of hyperarousal which, together with impaired fear extinction, is indeed one of the central components of the integrative etiology model for nightmares. However, it is still unclear, how exactly hyperarousal and nightmares interact, i.e., whether hyperarousal actually is a causal mechanism or rather a byproduct of other processes. Likewise, it is still unknown whether it can be influenced through interventions for nightmares, such as imagery rehearsal therapy or - directly during sleep - with some form of stimulation or targeted memory reactivation (TMR). The aim of the three studies that constitute my thesis was to examine biological correlates of nightmares, especially cortical hyperarousal in individuals with frequent nightmares from different samples and the effects of imagery rehearsal therapy (IRT) and TMR on physiological correlates and nightmare symptoms using polysomnography and high-density EEG-measurements. The first two studies focused on physiological correlates of nightmares and the effects of IRT. Study 1 addressed how physiological correlates differ between individuals with frequent nightmares and healthy controls and how an 8-week IRT group intervention influences nightmare symptoms and physiological correlates. Participants with frequent nightmares showed increased beta and gamma activity compared to healthy controls and their gamma activity during REM was reduced after the intervention. In study 2, a similar paradigm was used to investigate the effects of imagery rehearsal therapy as an add-on to inpatient treatment for individuals with borderline personality disorder. While this study did not show any changes in physiological correlates, the intervention group experienced a significantly more pronounced reduction in anxiety, intrusions and hyperarousal. Study 3 investigated the effects of experimentally manipulating these biological correlates. More specifically, whether reactivating a relaxation exercise with TMR in participants with frequent nightmares reduced hyperarousal and nightmare symptoms. While the reactivation did lead to a reduction in spindle count and density, another form of cortical hyperarousal, there was no influence on nightmare symptoms. Taken together, I could demonstrate that i) increased (cortical) arousal plays an important role as biological correlate and shows sensitivity to treatment in various samples with frequent nightmares (participants with frequent nightmares but no severe co-morbidities as well as individuals with borderline personality disorder and frequent nightmares), ii) IRT is successful in reducing gamma activity and psychological arousal alongside nightmare symptoms and iii) the reactivation of relaxation associated contents influences spindle activity which is even associated with changes in subjective sleep disturbance, indicating that this is a promising novel technique to target hyperarousal. Future research should therefore focus on further attempts to experimentally manipulate cortical hyperarousal by stimulation methods or by reactivating IRT and should also include other factors of the integrative model of nightmare etiology, especially fear extinction.