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Background: Social Zeitgeber Theory posits that disruptions in social rhythms can increase susceptibility to bipolar disorder (BD). Shift work (SW) is one of the external factors that cause instability in social rhythms and the sleep-wake cycle. This study evaluated the moderating influences of SW on the risks of BD and sleep-related parameters and depressive symptoms. Furthermore, we evaluated the specific work schedules including daytime, nighttime, and regular and irregular rotating SW., Methods: An online survey was administered to 6665 participants, with 3379 (50.7 %) classified as individuals with high scores of Mood Disorder Questionnaire (MDQ). The survey included the Pittsburgh Sleep Quality Index (PSQI), Insomnia Severity Scale (ISI), Epworth Sleepiness Scale (ESS), and Center for Epidemiologic Studies Depression Scale (CES-D)., Results: A multivariate regression model revealed significant interactive effects of MDQ positivity and SW on PSQI, ISI, and CES-D scores, but not ESS scores. In a secondary analysis of the high MDQ screen group, daytime workers had lower scores in sleep disturbances and depressive symptoms compared to those engaged in other forms of SW., Limitations: Online surveys were accessible voluntarily, leading to potential selection bias. Cross-sectional data identified associations, not causal relationships. Only a self-reported questionnaire was used., Conclusions: Our findings emphasize the advantages of a daytime work schedule for individuals at high risk of BD. In accordance with the principles of social rhythm interpersonal therapy, sleep interventions for individuals at high risk of BD should include the maintenance of a consistent daytime schedule., Competing Interests: Declaration of competing interest None., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Objective: We investigated the differences in fatigue and somatization between shift and non-shift workers and explored the effects of sleep and depression on fatigue and somatization in shift workers., Methods: In total, 4543 shift workers and 2089 non-shift workers completed self-reported questionnaires. The Center for Epidemiologic Studies Depression Scale (CESD), Pittsburgh Sleep Quality Index (PSQI), Fatigue Severity Scale (FSS), and Somatization subscale of the Symptom Checklist 90-item version (SCL-SOM) were used to measure depression, sleep quality, fatigue, and somatization, respectively. Fatigue and somatization were compared between shift and non-shift workers after controlling for different sets of covariates., Results: Compared to non-shift workers, shift workers reported higher FSS (mean difference: 2.19 ± 0.30, p < 0.01) and SCL-SOM (mean difference: 1.77 ± 0.21, p < 0.01) scores after controlling for age, gender, presence of medical illness, occupational category, monthly income, length of service, and weekly working hours. The between-group difference in FSS score was no longer significant after additionally controlling for CES-D (p = 0.15) or PSQI (p = 0.18). The between-group difference in SCL-SOM score showed only non-significant trends after additionally controlling for CES-D (p = 0.09) or PSQI (p = 0.07). The group difference in SCL-SOM scores disappeared after controlling for both CES-D and PSQI scores (p = 0.99)., Conclusions: Shift workers had higher fatigue and somatization levels than non-shift workers and the group difference was associated with disturbed sleep and depressed mood in shift workers., Competing Interests: Declaration of Competing Interest The authors declare no conflict of interest., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Object: We investigated burnout and associated factors in non-shift workers (NSWs), shift workers with regular rotating shifts (RRSWs), and shift workers with irregular or unpredictable rotating shifts (IRSWs)., Methods: In total, 5,125 adult workers (1,966 NSWs, 1,936 RRSWs, and 1,223 IRSWs) participated in an online self-reported survey. Job burnout and three dimensions thereof (exhaustion, cynicism, and professional efficacy) were assessed using the Maslach Burnout Inventory-General Survey (MBI-GS). The Center for Epidemiological Studies Depression Scale (CES-D) (depressive symptoms), Pittsburgh Sleep Quality Index (PSQI) (subjective sleep quality), and Korean Occupational Stress Scale (KOSS) (stressful job environment) were also used., Results: Both types of shift workers scored higher in terms of exhaustion, cynicism, and poor professional efficacy on the MBI-GS compared with NSWs after controlling for age and gender. IRSWs exhibited higher scores on the exhaustion and professional efficacy dimensions of the MBI-GS compared with RRSWs. After controlling for the CES-D and PSQI scores, we found no significant difference in cynicism among the groups. After controlling for the KOSS score, we found no significant difference in professional efficacy. All MBI-GS dimensional scores were correlated significantly with the CES-D, PSQI, and KOSS scores in all three groups., Conclusion: The job burnout level of rotating shift workers, especially those with irregular shifts, was higher than that of other workers. Cynicism in shift workers may be largely attributable to poor sleep or depression; the poor efficacy of shift workers may be explained by their stressful work environment., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Gu, Lee, Hwang, Kim, Lee and Kim.)

Introduction: Shift work is known to reduce productivity and safety at work. Previous studies have suggested that a variety of interrelated factors, such as mood, cognition, and sleep, can affect the performance of shift workers. This study aimed to identify potential pathways from depression, sleep, and cognition to work performance in shift and non-shift workers., Material and Methods: Online survey including the Center for Epidemiologic Studies Depression Scale (CES-D), Cognitive Failure Questionnaire (CFQ), and Pittsburgh Sleep Quality Index (PSQI), as well as two items representing work mistakes were administered to 4,561 shift workers and 2,093 non-shift workers. A multi-group structural equation model (SEM) was used to explore differences in the paths to work mistakes between shift and non-shift workers., Results: Shift workers had higher PSQI, CES-D, and CFQ scores, and made more mistakes at work than non-shift workers. The SEM revealed that PSQI, CES-D, and CFQ scores were significantly related to mistakes at work, with the CFQ being a mediating variable. There were significant differences in the path coefficients of the PSQI and CES-D between shift and non-shift workers. The direct effects of sleep disturbances on mistakes at work were greater in shift workers, while direct effects of depressive symptoms were found only in non-shift workers., Discussion: The present study found that shift workers made more mistakes at work than non-shift workers, probably because of depressed mood, poor sleep quality, and cognitive inefficiency. Sleep influences work performance in shift workers more directly compared to non-shift workers., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Yeo, Lee, Jeon, Lee, Hwang, Kim and Kim.)

Study Objectives: This study investigated the altered neural function involved in emotional interference and its role in linking sleep disturbance and depressive/anxiety symptoms in rotating shift workers., Methods: Sixty rotating shift workers and 61 controls performed the emotional Stroop task in three blocks (emotional-related, sleep-related, and neutral words) during functional magnetic resonance imaging (fMRI) assessments. Sleep disturbance and depressive/anxiety symptoms were assessed using self-report measures and sleep diaries. Actigraphy was used to assess the sleep and circadian variables. fMRI scans were performed to compare brain activation during the emotional Stroop task. The proposed moderating models were tested using the PROCESS macro in SPSS software., Results: A significant condition effect on reaction time was detected. Regardless of the group, reaction times were longer in the negative emotional word and sleep-related conditions than in the neutral word condition. Whole-brain analysis revealed that rotating shift workers show greater neural activation in the left dorsolateral prefrontal cortex (DLPFC) compared with controls while performing the emotional Stroop task with negative emotional words. Sleep disturbance was more strongly associated with depressive symptoms when activation of the left DLPFC was higher during the emotional Stroop task with negative words., Conclusions: The left DLPFC may play important roles in increased sensitivity to emotional information, possibly due to circadian misalignment, and has moderating effects on the association between sleep disturbance and depressive symptoms in rotating shift workers. These findings will help to identify possible brain regions where interventions can be performed to correct sleep and mood problems in rotating shift workers., (© The Author(s) 2022. Published by Oxford University Press on behalf of Sleep Research Society. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background: This study investigated the effects of anterior insula (AI) activation on the association between stress and sleep disturbance as a neurobiological basis of the trait-like degree of sleep reactivity to stress. Additionally, it examined the effects of AI activity on the association between sleep disturbance and depression., Methods: The participants were 48 adults. To assess AI activation in response to sleep-related stimuli (SS) compared to neutral stimuli (NS), we extracted mean AI parameter estimates for the SS-NS contrast. We examined whether the interaction between life stress and AI activation would predict sleep disturbance and whether the interaction between sleep disturbance and AI activation would predict depression., Results: At higher levels of bilateral AI activation in response to SS, higher levels of stress were associated with greater sleep disturbance (left AI x stress: b = 1.07, SE = 0.44, p < 0.05; right AI x stress: b = 1.05, SE = 0.48, p < 0.05). In addition, at higher levels of right AI activation, higher levels of sleep disturbance were associated with more severe depressive symptoms (right AI x sleep disturbance: b = 2.55, SE = 1.10, p < 0.05)., Limitation: This study assessed sleep quality and depressive symptoms based on self-reported questionnaires., Conclusion: This study revealed moderating effects of AI activation on the association between negative life stress and sleep disturbance. Additionally, AI activation strengthened the association between sleep disturbance and depression. AI activation may reflect a crucial etiological diathesis for insomnia and stress-related disorders., (Copyright © 2021. Published by Elsevier B.V.)

While previous studies have suggested that snoring may be associated with depressive symptoms and suicidality in adults and preschool children, there have been no investigations in non-clinical adolescent populations. This study aimed to demonstrate the association between snoring and depressive symptoms/suicidality in adolescents. This survey study recruited 8530 students (grades 7-11) and examined depressive symptoms, suicidality, snoring frequency, daytime sleepiness, sleep duration, and presence of insomnia by questionnaires. Correlation analyses, multiple linear regression analyses and mediation analyses were performed to determine the association between snoring frequency and depressive symptoms/suicidality. The study population included 8080 students (16.73 ± 1.09 years old). Snoring frequency was positively correlated with depressive symptoms and suicidality. Snoring frequency was associated with depressive symptoms and suicidality when adjusted for age and sex, and the association remained significant after additionally adjusting for sleep duration, insomnia, and daytime sleepiness. When depressive symptoms were included as a predictor of suicidality, snoring frequency showed no significant predictive value. Mediation analysis confirmed that depressive symptoms mediate the association between snoring frequency and suicidality. Our findings suggest that self-reported complaints of snoring are associated with increased depressive symptoms and suicidality in adolescents independently of sleep duration, insomnia, and daytime sleepiness, and the connection between snoring and suicidality is mediated by depressive symptoms. These data underscore the importance of identifying snorers among adolescents and screening for depression and suicidal ideation in this population., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Although fatigue is common in insomnia, the clinical associates of fatigue in patients with insomnia are largely unknown. We aimed to investigate the clinical associates of fatigue in patients with insomnia. Patients visiting the Stanford Sleep Medicine Center completed the Insomnia Severity Index (ISI), Insomnia Symptom Questionnaire (ISQ), the Fatigue Severity Scale (FSS), the Epworth Sleepiness Scale (ESS), and the Patient Health Questionnaire (PHQ-9). Among 6367 patients, 2024 were diagnosed with insomnia (age 43.06 ± 15.19 years; 1110 women and 914 men) according to the ISI and the ISQ. Insomnia patients with severe fatigue (n = 1306) showed higher insomnia symptoms, daytime sleepiness, depression and longer habitual sleep duration than those without severe fatigue (n = 718). Higher insomnia symptoms, daytime sleepiness and depressive symptoms, and longer habitual sleep duration, independently predicted higher fatigue scores. Among insomnia patients with daytime sleepiness (ESS≥10), only habitual sleep duration and depression predicted fatigue scores. The interaction between insomnia severity and daytime sleepiness significantly predicted the severity of fatigue. Depression was a significant mediator between insomnia and fatigue. For 598 insomnia patients undergoing overnight polysomnography (PSG), no significant correlations were found between fatigue and any PSG parameters. The current study suggests that managing insomnia or depression may reduce the fatigue of insomnia patients, whereas arbitrary efforts to prolong sleep duration may worsen their fatigue., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Objective: Defense mechanism may contribute to psychiatric symptoms. Refugees are vulnerable to various psychiatric symptoms, such as depression, anxiety, somatization, and those associated with post-traumatic stress disorder (PTSD), due to their traumatic or stressful experiences. We aimed to investigate the mediating role of each defense mechanism in the occurrence of specific psychiatric symptoms in North Korean refugees., Method: Among 213 North Korean refugees initially recruited, 201 completed the following questionnaires: the Defense Style Questionnaire, the Center for Epidemiological Studies-Depression Scale (CES-D), the State-Trait Anxiety Inventory-State (STAI-S), the somatization subscale of Symptom Check-List-90-Revised (SCL-90-R), and the Impact of Event Scale-Revised (IES-R). Stepwise regression analysis was performed to determine the defense mechanisms more predominantly associated with specific psychiatric symptoms after controlling for age, sex, number of traumatic experiences, and other psychiatric symptoms (depressive symptoms and/or anxiety)., Results: Higher levels of depression were independently predicted by greater use of resignation. More use of acting out and less use of humor and sublimation independently predicted higher levels of anxiety. Somatization was independently predicted by more use of inhibition. PTSD symptoms were independently predicted by more use of undoing and isolation., Conclusions: Specific psychiatric symptoms were associated with specific defense mechanisms in North Korean refugees. Our findings suggest that the manifest psychiatric symptoms of refugees may be mediated by their dominant defense mechanism., (Copyright © 2014. Published by Elsevier Inc.)

Studies have suggested that psychotic-like experiences (PLEs) are associated with behavioral problems in adolescents. The aim of this study was to investigate relationships between domains of PLEs, suicidal ideation, and depression in a large community sample of adolescents. The sample consisted of 8096 Korean subjects (3184 boys and 4912 girls) aged 14 to 19 years. The level of PLEs, depression, and suicidal ideation were assessed by the Eppendorf schizophrenia inventory (ESI), Beck's depression inventory, and Beck's scale for suicidal ideation, respectively. Both the level of depression and suicidal ideation were significantly associated with PLEs. Among the four domains of the ESI, the deviant perception, ideas of reference, and auditory uncertainty were associated with the suicidal ideation. Additionally, subjects with more PLEs had significantly more suicidal ideation and depressive symptoms. PLEs in adolescents are associated with potential risk of suicide and depressive symptoms significantly mediated the association between suicidal ideation and PLEs. The presence of perceptual disturbances, ideas of reference, and depression may be regarded as warning signs for suicide-related behaviors., (Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.)

Objectives: We aimed to investigate the moderating effect of age on the association of morningness-eveningness with depression in subjects with a broad range of ages. The hypothesis of the current study was that there would be a relationship between depressive symptoms and eveningness, especially in young age groups., Methods: Three hundred sixty-one subjects (male/female=140/221) from 19 to 79 years of age participated in the study. Subjects were separated into five age groups: (1) < or = 20s (n=70), (2) 30s (n=85), (3) 40s (n=97), (4) 50s (n=54) and 5) > or = 60s (n=55). The Horne-Osteberg Morningness-Eveningness Questionnaire (MEQ) and the Center for Epidemiological Studies for Depression Scale (CES-D) were administered to all subjects., Results: MEQ showed a significantly independent and negative association with CES-D (beta=-.27, P<.001), which meant the association between eveningness and depressive symptoms. The negative association between MEQ and CES-D were significant in < or = 20s (beta=-.31, P=.01), 50s (beta=-.38, P<.01) and > or = 60s (beta=-.35, P<.01), while there was no significant association between MEQ and CES-D in 30s (beta=-.06, P=.56) and 40s (beta=-.10, P=.32)., Conclusion: Our findings demonstrate an association of depressive symptoms with eveningness, which was more prominent in younger or older aged than in middle aged. Our findings suggest that the association between depressive symptoms and eveningness might be moderated by age., (2010 Elsevier Inc. All rights reserved.)

The current study investigated differences in the regional gray matter (GM) volume of specific thalamic nuclei between North Korean (NK) refugees and South Korean (SK) residents. It also investigated associations between thalamic GM volume changes and psychological symptoms. Psychological evaluations and magnetic resonance imaging were conducted on 50 traumatized NK refugees and 55 non-traumatized SK residents. The regional GM volume ratios in the bilateral thalami were calculated for all participants using voxel-based morphometry. NK refugees showed greater GM volume ratios in the right medial-posterior nuclei and left medial nuclei compared with SK residents. NK refugees also exhibited more depressive symptoms than SK residents. However, increased GM volume ratios in both right medial-posterior nuclei and left medial nuclei were correlated with fewer depressive symptoms in NK refugees, but not in SK residents. The findings indicate that traumatized NK refugees had increased GM volumes in the right medial-posterior nuclei and left medial nuclei, which were associated with fewer depressive symptoms. The enlarged specific thalamic nuclei presented among refugees in the current study might be associated with a neurobiological compensatory mechanism that prevents the development or progression of depression in refugees after repetitive traumatic experiences. [ABSTRACT FROM AUTHOR]

Background: Early life traumatic events and recent stressful events are known to have especially strong effects on emotional wellbeing. However, little is known about the interaction of early and recent stressors on emotions. We aimed to examine the interactive effects of early trauma and recent stressors on depression, anxiety, and anger. Methods: One hundred and seventy adults were recruited and asked to complete the Center for Epidemiological Studies Depression Scale (CES-D), the state anxiety subscale of the State–Trait Anxiety Inventory (STAI-S), and the state anger subscale of the State–Trait Anger Expression Inventory (STAXI-S). Early traumas and recent stressors were assessed during face-to-face interviews. Multiple regression analysis was performed to test whether early trauma, recent stressors, and the interaction of the two would predict CES-D, STAI-S, and STAXI-S scores. Results: In the multiple regression models, STAI-S scores were predicted only by recent stressors (R2 = 0.063, p = 0.001). In contrast, CES-D and STAXI-S scores were predicted only by the synergistic interaction of early trauma with recent stressors (R2 = 0.075, p < 0.001; R2 = 0.039, p = 0.01, respectively). Conclusions: A synergistic interaction effect between early trauma and recent stressful events on current depression and anger was observed, indicating that the combined effects of early trauma and recent stressors are stronger than their individual effects. In contrast, anxiety was affected mainly by recent stressors. Our findings suggest that the form that emotional disturbance takes can vary depending on the timing of stressors. [ABSTRACT FROM AUTHOR]

Abstract: Objective: We compared the biogenetic temperaments and characters of primary insomnia patients, major depressive disorder (MDD) patients with insomnia, MDD patients without insomnia, and normal controls. Methods: A total of 417 participants were recruited from a community and a psychiatric clinic in South Korea. Subjects were divided into 4 groups based on the Structured Clinical Interview for DSM-IV axis I disorder (SCID-IV) and sleep questionnaire: 1) normal controls (n=314), 2) primary insomnia (n=33), 3) MDD without insomnia (n=30), and 4) MDD with insomnia (n=40). All participants were requested to complete the Temperament and Character Inventory. Results: There were significant between-group differences in harm avoidance (HA)(F=32.96, p<0.001), reward dependence (RD)(F=5.21, p<0.01), self-directedness (SD)(F=24.72, p<0.001) and cooperativeness (CO)(F=15.75, p<0.001), after controlling for age and gender. Subjects with primary insomnia showed higher HA and lower SD than normal control, but lower HA and higher SD than MDD patients with insomnia. CO was lower in MDD patients, but not in subjects with primary insomnia. Lower RD was found only in MDD patients with insomnia. Conclusion: The current study suggests that high HA and low SD were related to primary insomnia, although these patterns were more prominent in patients with MDD. [Copyright &y& Elsevier]

This study explored sleep disturbances and depression among various types of shift workers (SWs) and non-SWs, focusing on work schedule diversity. We enrolled 6,654 adults (4,561 SWs, 2,093 non-SWs). Based on self-report questionnaires on work schedules, the participants were classified according to shift work type: non-shift work; and fixed evening, fixed night, regularly rotating, irregularly rotating, casual, and flexible shift work. All completed the Pittsburgh Sleep Quality Index (PSQI), Epworth Sleepiness Scale (ESS), Insomnia Severity Index (ISI), and short-term Center for Epidemiologic Studies-Depression scale (CES-D). SWs reported higher PSQI, ESS, ISI, and CES-D than non-SWs. Fixed SWs (fixed evenings and fixed nights) and true SWs (regularly and irregularly rotating SWs) scored higher on the PSQI, ISI, and CES-D than non-SWs. True SWs scored higher on the ESS than fixed SWs and non-SWs. Among fixed SWs, fixed night SWs scored higher on the PSQI and ISI than fixed evening SWs. Among true SWs, irregular SWs (irregularly rotating and casual SWs) scored higher on the PSQI, ISI, and CES-D compared to regularly rotating SWs. The PSQI, ESS, and ISI independently were associated with the CES-D of all SWs. We found an interaction between the ESS and the work schedule on the one hand, and the CES-D on the other, which was stronger in SWs than non-SWs. Fixed night and irregular shifts were linked with sleep disturbances. The depressive symptoms of SWs are associated with sleep problems. The effects of sleepiness on depression were more prominent in SWs than non-SWs. [ABSTRACT FROM AUTHOR]