{"id":{"repo_id":"radboud","oai_identifier":"oai:repository.ubn.ru.nl:2066/329175"},"canonical_url":"https://search.dev.ndltd.org/etd/radboud/oai:repository.ubn.ru.nl:2066/329175","repository":{"repo_id":"radboud","name":"Radboud University Nijmegen","base_url":"https://repository.ubn.ru.nl/oai/request"},"display":{"title":"The bidirectional relationship between sleep and affect: The role of emotion regulation","abstract":"Contains fulltext : 329175.pdf (Publisher’s version ) (Open Access)","abstract_html":"Contains fulltext : 329175.pdf (Publisher’s version ) (Open Access)","abstract_has_math":false,"creators":["Boon, M.E."],"institution":"S.l. : s.n.","degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":["Geurts, S.A.E.","Vink, J.M.","Hooff, M.L.M. van"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2026,"date_issued":"2026","date_published":"2026","updated_at":"2026-07-24T04:03:01Z","subjects":["Work, Health and Performance"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://hdl.handle.net/2066/329175","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Geurts, S.A.E.","Vink, J.M.","Hooff, M.L.M. van"]},{"key":"dc:creator","label":"Author","values":["Boon, M.E."]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2026"]},{"key":"dc:publisher","label":"Institution","values":["S.l. : s.n."]},{"key":"dc:type","label":"Dc Type","values":["Doctoral thesis"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Work, Health and Performance"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://repository.ubn.ru.nl//bitstream/handle/2066/329175/329175.pdf","https://hdl.handle.net/2066/329175"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Contains fulltext : 329175.pdf (Publisher’s version ) (Open Access)","Sleep is a fundamental biological process that plays a crucial role in both physical and mental health, and is frequently associated with emotional functioning. Although the link between sleep and positive affect (i.e., pleasant emotions, such as joy, enthusiasm, and contentment) and negative affect (i.e., unpleasant emotions, such as sadness, anger, and anxiety) appears intuitive, empirical findings remain inconsistent—especially when studies rely on objective sleep measures rather than self-reports. Most prior research has centered on sleep deprivation or duration, leaving other aspects of sleep quality—such as fragmentation and regularity—underexplored. Similarly, although poor sleep is often associated with changes in affect, the mechanisms through which sleep influences emotional states are not fully understood. Emotion regulation may serve as a key pathway, but existing findings are inconsistent. To address these gaps, this thesis had three main aims: (1) to assess the relationship between objective sleep fragmentation and positive and negative affect, (2) to investigate the role of sleep regularity in positive and negative affect, and (3) to explore whether emotion regulation acts as a mechanism linking sleep and affect. Across three chapters, a combination of experimental, longitudinal, and ecological momentary assessment methods was used to examine these relationships more closely. Aim 1: Mixed evidence for objective sleep metrics and affect — assessing objective sleep fragmentation Although self-report studies show a bidirectional relationship between poor sleep and affect—whereby poor sleep predicts more negative and less positive affect, and vice versa—findings are more inconsistent when sleep is assessed objectively. This inconsistency may partly result from an overemphasis on sleep duration rather than sleep quality, even though increasing evidence points to sleep quality as a more reliable predictor of emotional well-being. One key indicator of reduced sleep quality is sleep fragmentation, which refers to brief awakenings that interrupt the normal progression through sleep stages. In particular, REM sleep, which plays a central role in processing emotional experiences, appears especially sensitive to fragmentation. Disruptions in REM sleep may interfere with the overnight regulation of emotional distress and have been linked to increased negative affect and symptoms of depression. Despite this, both general and REM-specific sleep fragmentation have received little attention in naturalistic studies. This thesis therefore investigated how objectively measured sleep fragmentation in general, and REM sleep fragmentation in particular, relate to daily positive and negative affect. In relation to the first aim, in Chapter 2 we conducted an experimental study in which participants experienced one night of sleep fragmentation (i.e., being woken up every 80 minutes) and one control night, with positive and negative affect assessed four times the following day. Results showed that one night of fragmented sleep led to a decrease in positive affect the following day, while negative affect remained unaffected. In Chapter 3, we conducted a longitudinal field study to assess the bidirectional link between REM sleep fragmentation and negative and positive affect. Each participant wore an EEG headband for 15 nights, underwent polysomnography on 3 of those nights, and reported their momentary negative and positive affect every night. Results of this study showed no significant association between REM sleep fragmentation and next-day positive and negative affect. Interestingly, results did show that higher levels of negative affect before sleep were associated with more fragmented REM sleep during the night. No such relationship was found for pre-sleep positive affect. Together, these results demonstrate that one night of sleep fragmentation lowers positive affect and highlight REM sleep fragmentation’s sensitivity to negative emotional states. Aim 2: Objective sleep regularity and affect Another underexplored factor in the sleep–affect relationship is sleep regularity, referring to how consistently someone goes to bed and wakes up. Irregular sleep patterns—common in individuals with an evening chronotype whose natural rhythm conflicts with early school or work obligations—can disrupt the circadian system, which is closely tied to both sleep quality and mood. These misalignments may lead to poorer sleep quality and emotional well-being. However, it remains unclear whether sleep regularity influences mood on a daily basis or only over longer periods, as findings in the literature are mixed. To address this, the second aim of this thesis was to examine the relationship between objectively measured sleep regularity and daily affect. Results showed that greater sleep regularity across a two-day window predicted lower negative affect the following day, but no associations were found with positive affect or with sleep regularity measured over a 28-day period. These findings suggest that sleep regularity may influence affect in the short term and is sensitive to day-to-day fluctuations. Aim 3: Emotion regulation as a potential mechanism In addition to mixed findings on how sleep relates to affect, little is known about the mechanisms driving this relationship. One proposed pathway is emotion regulation—the strategies people use to manage their emotions, such as reappraisal, acceptance, or distraction. These are generally adaptive and associated with better mood, while maladaptive strategies like rumination or suppression are linked to more negative affect and mental health risk. Poor sleep may impair emotion regulation by weakening top-down control in the brain, making it harder to use helpful strategies. However, most research has focused on sleep deprivation (instead of sleep quality) and narrow measures (mainly reappraisal), limiting our understanding. No studies have yet tested whether daily changes in emotion regulation help explain how sleep affects next-day affect. To explore this, the third aim of this thesis was to examine whether emotion regulation acts as a mechanism in the sleep–affect link. Findings showed that sleep fragmentation did not impair the ability to use common strategies like reappraisal, acceptance, or distraction. However, it did increase the use of rumination and distraction, and importantly, rumination mediated the link between poor sleep and higher next-day negative affect. No such effects were found for positive affect. In the second study, no relationship was found between sleep regularity and emotion regulation. Together, these results suggest that poor sleep may not directly impair the implementation of regulation strategies, but it may influence the type of strategies individuals choose—especially increasing maladaptive patterns such as rumination. Limitations A key limitation of this thesis is the relatively small sample sizes in Chapters 3 and 4, due to the high cost and time demands of polysomnography, which reduces statistical power. Additionally, most participants were healthy university students, making it harder to detect strong links between sleep and affect compared to clinical populations. To manage the sample size, the complexity of sleep, affect, and emotion regulation variables was simplified, potentially overlooking important nuances—since sleep involves many dimensions, affect varies in valence and arousal, and emotion regulation includes multiple stages beyond broad strategy use. Moreover, traditional sleep scoring methods may miss subtle, dynamic changes in sleep architecture, and newer techniques such as time-series analysis and machine learning could offer richer insights. Future research Building on these limitations, future research should investigate how poor sleep impacts various stages of emotion regulation, including emotional awareness, goal evaluation, and the flexible selection and use of regulation strategies across situations. It is important to study not only the frequency of strategy use but also how flexibly people adapt them to different contexts. Larger and more diverse samples with repeated measurements will better capture changes over time. Combining objective and subjective sleep data with more detailed tracking of discrete emotions—rather than broad positive and negative categories—will provide deeper insights. Practical Implications This thesis highlights the importance of targeting both sleep quality and rumination in interventions. Poor sleep can increase rumination, which in turn raises negative affect, potentially creating a vicious cycle with fragmented REM sleep. Early interventions focusing on improving sleep hygiene—like consistent bedtimes and stress management—and reducing rumination through approaches like Rumination-Focused Cognitive Behavioral Therapy show promise in preventing mood disturbances. On a societal level, promoting more regular sleep schedules is crucial. Current rigid work and school hours often conflict with natural sleep rhythms, especially for evening types and adolescents, leading to irregular sleep and poor emotional health. Delaying school start times and allowing flexible work hours can better align schedules with biological needs, improving sleep quality, mood, and overall well-being. Conclusion This thesis provides new insights into the complex relationship between sleep, affect, and emotion regulation. While not all hypotheses were confirmed, the results emphasize that fragmented and irregular sleep can undermine emotional well-being—primarily by increasing rumination and disrupting REM sleep. Rumination, in particular, emerged as a mechanism linking poor sleep to higher negative affect. Although no consistent associations were found for other regulation strategies, the findings point to the need for a broader, more nuanced understanding of how sleep interacts with emotional processes. Ultimately, improving sleep quality and promoting emotion regulation flexibility may serve as important pathways for enhancing mental well-being and preventing mood disorders in both clinical and everyday settings.","Radboud University, 23 maart 2026","Promotores : Geurts, S.A.E., Vink, J.M. Co-promotor : Hooff, M.L.M. van","126 p."]},{"key":"dc:title","label":"Title","values":["The bidirectional relationship between sleep and affect: The role of emotion regulation"]}]}],"canonical_facts":{"dc:contributor":["Geurts, S.A.E.","Vink, J.M.","Hooff, M.L.M. van"],"dc:creator":["Boon, M.E."],"dc:date":["2026"],"dc:description":["Contains fulltext : 329175.pdf (Publisher’s version ) (Open Access)","Sleep is a fundamental biological process that plays a crucial role in both physical and mental health, and is frequently associated with emotional functioning. Although the link between sleep and positive affect (i.e., pleasant emotions, such as joy, enthusiasm, and contentment) and negative affect (i.e., unpleasant emotions, such as sadness, anger, and anxiety) appears intuitive, empirical findings remain inconsistent—especially when studies rely on objective sleep measures rather than self-reports. Most prior research has centered on sleep deprivation or duration, leaving other aspects of sleep quality—such as fragmentation and regularity—underexplored. Similarly, although poor sleep is often associated with changes in affect, the mechanisms through which sleep influences emotional states are not fully understood. Emotion regulation may serve as a key pathway, but existing findings are inconsistent. To address these gaps, this thesis had three main aims: (1) to assess the relationship between objective sleep fragmentation and positive and negative affect, (2) to investigate the role of sleep regularity in positive and negative affect, and (3) to explore whether emotion regulation acts as a mechanism linking sleep and affect. Across three chapters, a combination of experimental, longitudinal, and ecological momentary assessment methods was used to examine these relationships more closely. Aim 1: Mixed evidence for objective sleep metrics and affect — assessing objective sleep fragmentation Although self-report studies show a bidirectional relationship between poor sleep and affect—whereby poor sleep predicts more negative and less positive affect, and vice versa—findings are more inconsistent when sleep is assessed objectively. This inconsistency may partly result from an overemphasis on sleep duration rather than sleep quality, even though increasing evidence points to sleep quality as a more reliable predictor of emotional well-being. One key indicator of reduced sleep quality is sleep fragmentation, which refers to brief awakenings that interrupt the normal progression through sleep stages. In particular, REM sleep, which plays a central role in processing emotional experiences, appears especially sensitive to fragmentation. Disruptions in REM sleep may interfere with the overnight regulation of emotional distress and have been linked to increased negative affect and symptoms of depression. Despite this, both general and REM-specific sleep fragmentation have received little attention in naturalistic studies. This thesis therefore investigated how objectively measured sleep fragmentation in general, and REM sleep fragmentation in particular, relate to daily positive and negative affect. In relation to the first aim, in Chapter 2 we conducted an experimental study in which participants experienced one night of sleep fragmentation (i.e., being woken up every 80 minutes) and one control night, with positive and negative affect assessed four times the following day. Results showed that one night of fragmented sleep led to a decrease in positive affect the following day, while negative affect remained unaffected. In Chapter 3, we conducted a longitudinal field study to assess the bidirectional link between REM sleep fragmentation and negative and positive affect. Each participant wore an EEG headband for 15 nights, underwent polysomnography on 3 of those nights, and reported their momentary negative and positive affect every night. Results of this study showed no significant association between REM sleep fragmentation and next-day positive and negative affect. Interestingly, results did show that higher levels of negative affect before sleep were associated with more fragmented REM sleep during the night. No such relationship was found for pre-sleep positive affect. Together, these results demonstrate that one night of sleep fragmentation lowers positive affect and highlight REM sleep fragmentation’s sensitivity to negative emotional states. Aim 2: Objective sleep regularity and affect Another underexplored factor in the sleep–affect relationship is sleep regularity, referring to how consistently someone goes to bed and wakes up. Irregular sleep patterns—common in individuals with an evening chronotype whose natural rhythm conflicts with early school or work obligations—can disrupt the circadian system, which is closely tied to both sleep quality and mood. These misalignments may lead to poorer sleep quality and emotional well-being. However, it remains unclear whether sleep regularity influences mood on a daily basis or only over longer periods, as findings in the literature are mixed. To address this, the second aim of this thesis was to examine the relationship between objectively measured sleep regularity and daily affect. Results showed that greater sleep regularity across a two-day window predicted lower negative affect the following day, but no associations were found with positive affect or with sleep regularity measured over a 28-day period. These findings suggest that sleep regularity may influence affect in the short term and is sensitive to day-to-day fluctuations. Aim 3: Emotion regulation as a potential mechanism In addition to mixed findings on how sleep relates to affect, little is known about the mechanisms driving this relationship. One proposed pathway is emotion regulation—the strategies people use to manage their emotions, such as reappraisal, acceptance, or distraction. These are generally adaptive and associated with better mood, while maladaptive strategies like rumination or suppression are linked to more negative affect and mental health risk. Poor sleep may impair emotion regulation by weakening top-down control in the brain, making it harder to use helpful strategies. However, most research has focused on sleep deprivation (instead of sleep quality) and narrow measures (mainly reappraisal), limiting our understanding. No studies have yet tested whether daily changes in emotion regulation help explain how sleep affects next-day affect. To explore this, the third aim of this thesis was to examine whether emotion regulation acts as a mechanism in the sleep–affect link. Findings showed that sleep fragmentation did not impair the ability to use common strategies like reappraisal, acceptance, or distraction. However, it did increase the use of rumination and distraction, and importantly, rumination mediated the link between poor sleep and higher next-day negative affect. No such effects were found for positive affect. In the second study, no relationship was found between sleep regularity and emotion regulation. Together, these results suggest that poor sleep may not directly impair the implementation of regulation strategies, but it may influence the type of strategies individuals choose—especially increasing maladaptive patterns such as rumination. Limitations A key limitation of this thesis is the relatively small sample sizes in Chapters 3 and 4, due to the high cost and time demands of polysomnography, which reduces statistical power. Additionally, most participants were healthy university students, making it harder to detect strong links between sleep and affect compared to clinical populations. To manage the sample size, the complexity of sleep, affect, and emotion regulation variables was simplified, potentially overlooking important nuances—since sleep involves many dimensions, affect varies in valence and arousal, and emotion regulation includes multiple stages beyond broad strategy use. Moreover, traditional sleep scoring methods may miss subtle, dynamic changes in sleep architecture, and newer techniques such as time-series analysis and machine learning could offer richer insights. Future research Building on these limitations, future research should investigate how poor sleep impacts various stages of emotion regulation, including emotional awareness, goal evaluation, and the flexible selection and use of regulation strategies across situations. It is important to study not only the frequency of strategy use but also how flexibly people adapt them to different contexts. Larger and more diverse samples with repeated measurements will better capture changes over time. Combining objective and subjective sleep data with more detailed tracking of discrete emotions—rather than broad positive and negative categories—will provide deeper insights. Practical Implications This thesis highlights the importance of targeting both sleep quality and rumination in interventions. Poor sleep can increase rumination, which in turn raises negative affect, potentially creating a vicious cycle with fragmented REM sleep. Early interventions focusing on improving sleep hygiene—like consistent bedtimes and stress management—and reducing rumination through approaches like Rumination-Focused Cognitive Behavioral Therapy show promise in preventing mood disturbances. On a societal level, promoting more regular sleep schedules is crucial. Current rigid work and school hours often conflict with natural sleep rhythms, especially for evening types and adolescents, leading to irregular sleep and poor emotional health. Delaying school start times and allowing flexible work hours can better align schedules with biological needs, improving sleep quality, mood, and overall well-being. Conclusion This thesis provides new insights into the complex relationship between sleep, affect, and emotion regulation. While not all hypotheses were confirmed, the results emphasize that fragmented and irregular sleep can undermine emotional well-being—primarily by increasing rumination and disrupting REM sleep. Rumination, in particular, emerged as a mechanism linking poor sleep to higher negative affect. Although no consistent associations were found for other regulation strategies, the findings point to the need for a broader, more nuanced understanding of how sleep interacts with emotional processes. Ultimately, improving sleep quality and promoting emotion regulation flexibility may serve as important pathways for enhancing mental well-being and preventing mood disorders in both clinical and everyday settings.","Radboud University, 23 maart 2026","Promotores : Geurts, S.A.E., Vink, J.M. Co-promotor : Hooff, M.L.M. van","126 p."],"dc:identifier":["https://repository.ubn.ru.nl//bitstream/handle/2066/329175/329175.pdf","https://hdl.handle.net/2066/329175"],"dc:publisher":["S.l. : s.n."],"dc:subject":["Work, Health and Performance"],"dc:title":["The bidirectional relationship between sleep and affect: The role of emotion regulation"],"dc:type":["Doctoral thesis"]},"updated_at":"2026-07-24T04:03:01Z"}