Ho, Jonas Chan Wai
(2024)
Examining negative emotional states, daytime drowsiness & resting-state cognition on resting-state EEG patterns & sleep quality in young & older adults.
MRes thesis, University of Nottingham Malaysia.
Abstract
As individuals age, sleep quality is reported to decrease compared to earlier stages of life. these declines often coincide with an increase in the incidences of poor health outcomes, including physiological, psychological and neurodegenerative disorders. given the critical link between sleep quality and health in ageing, addressing sleep concerns may be vital to encourage healthier ageing. however, it is important to recognise the reciprocal relationship between these factors. poor lifestyle factors and illness can create sleep disturbances, while poor sleep quality may also exacerbate health conditions. therefore, it is vital to consider whether poor sleep quality necessarily worsens with age, which may serve as a catalyst for age-related pathologies, or if the onset of such pathologies may exacerbate sleep disturbances, leading to a cycle of declining health and sleep quality.
further complexity arises in the exploration of these variables, as the brain regions responsible for arousal and sleep regulation deteriorate with age. currently, there is limited research examining whether such deterioration results in changes in sleep patterns or manifests as abnormal arousal regulation, let alone whether these factors should be a concern when understanding the development of poor sleep outcomes in older adults. while efforts exist to investigate the relationships between arousal regulation, the development of poor sleep outcomes, and affective disorders, these parameters have not been explicitly studied in older populations. additionally, the tools used to examine changes in sleep quality are complicated by a lack of standardisation in methods, particularly concerning eeg measurements for monitoring brain activity and its associations with various forms of waking cognition and psychological health.
to begin address these complex relationships, this thesis investigates whether negative emotional states, daytime drowsiness, resting-state cognition, and specific features of resting-state eeg can explain variations in sleep quality. moreover, it explores whether these factors produce differential effects in young versus older adults. the need for age-group contrasts is important, as comparing these variables between younger and older adults may identify age-specific drivers. this can highlight factors unique to older age that contribute to the development of sleep deficits and their unique impact on older adults. such comparisons would also determine if the same tools used to investigate these variables in younger adults can be robustly applied to older adults. the primary focus of this study is to discern whether there may be age-exclusive factors that impact sleep quality in the absence of large pathologies, such as sleep and psychiatric disorders.
this thesis is structured around three primary goals. firstly, to investigate the relationships between sleep quality, negative emotional states, daytime drowsiness, and resting-state cognition. secondly, to explore whether the arousal regulation hypothesis can serve as a model for implicating age-related changes in the brain, and how it may provide links between psychological dimensions and sleep quality. lastly, this thesis aims to address the methodological considerations regarding resting-state eeg components, and consolidate contemporary best practices for age-related comparisons and highlight their importance in understanding the ageing brain.
the present study included 23 healthy young adults (aged 18-30) and 22 healthy older adults (over 60 years old). participants completed the psqi for subjective sleep quality, the dass to measure symptoms of depression, anxiety, and stress, and the ess to assess the severity of daytime drowsiness. they also underwent a 20-minute eyes-closed resting-state eeg recording, followed by a post-recording arsq questionnaire to measure their resting- state cognition. arousal regulation measures were extracted from the resting-state eeg recordings using vigall 2.1. specific features of the eeg signal, including periodic and aperiodic components, were processed via the fooof algorithm to enable comparisons of alpha and theta power. further scrutiny was performed to examine the conventional approach versus the individualised approach in bandwidth power comparisons, a consideration vital for cross age-group comparisons. lastly, elastic net regression was performed to develop age- group models, aiming to better understand the effects of various variables on sleep quality, and to identify if there were any differentiated predictors of sleep quality between young and older adults.
the findings of this thesis challenge the notion that poor sleep quality is an inevitable consequence of ageing. contrary to previous literature, the older adults in this sample did not exhibit significantly worse sleep compared to young adults and reported fairly good scores across most indices, consistent with the absence of large pathologies. in addition to that, no age-group differences emerged in arousal regulation patterns, despite robust age-group differences in sleep quality and negative emotional states. this suggests that changes in arousal regulation may not solely depend on the severity of negative emotional states (e.g., depression) but may be modulated only in individuals with affective disorders. this finding provides valuable insight into the utilisation of the vigall and enriches the understanding of the arousal regulation hypothesis. furthermore, extensive comparisons between conventional and parameterised approaches to eeg spectral analysis underscore the importance of individualised definitions of frequency bands and the need for standardisation of methods, particularly when comparing spectral properties between young and older adults. notably, the parameterisation and individualisation of eeg signals eliminated age-group effects observed with conventional approaches, indicating that conventional methods may conflate eeg signal properties and lead to misinterpretations. this is crucial for a better understanding of the underlying neural mechanisms that may influence sleep quality.
overall, these results suggest that age may not be the sole driver of sleep quality differences as commonly reported. instead, future research should explore age-related pathology in relation to sleep, rather than simply attributing sleep changes to ageing. additionally, this thesis demonstrates the importance of considering age-related sensitivities in eeg measures. failure to account for such sensitivities could lead to misinterpretation of findings, making it challenging to draw meaningful conclusions, especially in the context of age and sleep quality.
| Item Type: |
Thesis (University of Nottingham only)
(MRes)
|
| Supervisors: |
Chen, Po Ling |
| Keywords: |
aging, sleep quality, health outcomes, physiological disorders, psychological disorders, neurodegenerative disorders, healthy aging, reciprocal relationship, lifestyle factors, sleep disturbances |
| Subjects: |
B Philosophy. Psychology. Religion > BF Psychology |
| Faculties/Schools: |
University of Nottingham, Malaysia > Faculty of Science and Engineering — Science > School of Psychology |
| Item ID: |
78491 |
| Depositing User: |
Ho, Jonas
|
| Date Deposited: |
27 Jul 2024 04:40 |
| Last Modified: |
27 Jul 2024 04:40 |
| URI: |
https://eprints.nottingham.ac.uk/id/eprint/78491 |
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