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phd_wickaz
Doctoral thesis

The power of reactivations of memory cues, concepts of pre-sleep appraisals, and emotions during sleep

PSPE

  • [Fribourg (Switzerland)], [2025]

1 Online-Ressource (XVII, 191 Seiten)

PhD: Universität Freiburg (Schweiz), 03.06.2025

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English Sleep is important for processing memories and emotions. It is widely assumed that during sleep, particularly during slow-wave sleep (SWS), newly acquired memory traces are spontaneously reactivated, thereby supporting their consolidation and stabilization. Beyond memory traces, the Memories-of-Sleep (MemoSleep-) Hypothesis suggests that cognitive concepts are also reactivated during sleep. The repeated reactivations of these concepts potentially influence sleep quality by either impairing or improving sleep, depending on the particular content of these concepts. However, it remains unclear whether memory reactivations occur primarily during SWS or whether the non-rapid eye movement (NREM) sleep stage N2 is also involved. Additionally, the exact nature of sleep disturbances induced by unfamiliar environments, particularly over non-consecutive nights, has not yet been fully characterized and explained by the MemoSleep-Hypothesis. Finally, the influence of emotions on sleep within the context of the MemoSleep-Hypothesis remains to be clarified. This dissertation addresses these research gaps through three independent sleep studies. The first study investigated the contribution of memory reactivation during NREM sleep stage N2 compared to SWS. However, no significant difference was found between words that were externally reactivated during N2 and those reactivated during SWS. Moreover, there was no overall memory benefit from targeted memory reactivation (TMR) during sleep. The second study examined sleep disturbances during the first night in an unfamiliar environment, known as the First-Night Effect (FNE), as an example of the reactivation of stressful mental concepts during sleep. The results show that an FNE exists also in non-consecutive nights and even occurs in familiar environments. However, prior familiarization with the recording equipment was found to attenuate the FNE. The third study explored, for the first time, whether musical chords associated with varying emotional ratings can elicit different brain responses during sleep. The results confirmed that the sleeping brain is capable of differentially processing specific musical chords. The results of this dissertation challenge the specific role of SWS in memory reactivation during sleep. Additionally, they demonstrate that unfamiliar sleep environments generally impact sleep quality, however, a habituation occurs even over non-consecutive nights. Finally, these findings pave the way for novel approaches to using emotion-associated musical stimuli to influence activated mental concepts during sleep, providing new knowledge and a foundation for further refinements and future research directions within the framework of the MemoSleep-Hypothesis.
Faculty
Faculté des lettres et des sciences humaines
Department
Département de Psychologie
Language
  • English
Classification
Psychology
Notes
  • Literaturverzeichnis
License
CC BY
Open access status
diamond
Identifiers
Persistent URL
https://folia.unifr.ch/unifr/documents/332719
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