REVIEWERS' COMMENTS AND RESPONSES

Dear Reviewers, we value your thorough and perceptive comments on our manuscript. To improve the manuscript's readability, clarity, and contribution, we have carefully considered every suggestion and made significant changes. Our answers to each of the points made are listed below;

REVIEWER #1:

Thank you for giving me the opportunity to review this manuscript.

1) While the term "work-related stress" (WRS) is introduced, the definition is not clearly explained or supported by a more thorough background. It is better to describe more details or a broader literature context on how WRS is specifically measured or categorized in the studies referenced.

Response

We thank the reviewer for this insightful comment. We have revised the introduction to provide a clearer and more detailed explanation of work-related stress (WRS), including how it is defined and commonly assessed in the literature. We have also updated the description of key studies to clarify how WRS was operationalized in each. We have indicated in the revised manuscript draft that:

“Defined by [9] as emotional, cognitive, behavioral, and physiological responses to negative aspects of work, WRS reflects a state of heightened arousal and distress. It often arises from persistent job demands such as excessive workload, role ambiguity, low job control, and employment insecurity [9]. Although short-term stress responses, such as fatigue, elevated heart rate, and negative affect, are common and typically harmless, they do not disrupt sleep when the body adequately recovers during off-job periods. However, sleep may be impaired when stress recovery is insufficient and physiological systems, such as the hypothalamic-pituitary-adrenocortical and sympathetic-adrenal-medullary axes, remain activated during rest periods [10]. This prolonged activation contributes to cumulative biological strain, which can ultimately result in serious health conditions [11]. WRS, including high-strain, low-control, or effort-reward imbalance situations without adequate recovery has been shown to predict poor sleep outcomes across various populations [12,13]. For instance, a mid-life Australian cohort study found that job stress, assessed via the Job Content Questionnaire (JCQ), independently predicted chronic sleep disturbances [12], while a systematic review of 38 studies confirmed a consistent negative association between WRS and sleep quality [14]. Among Chinese oilfield workers, occupational stress, which was assessed using the Occupational Stress Inventory-Revised (OSI-R) scale, capturing role overload, role ambiguity, and responsibility was positively associated with increased sleep [15]”

2) The introduction mentions that data on WRS and sleep problems (SP) in LMICs, particularly in Ghana, is scarce, but it does not explain why this gap is so significant. A clearer discussion of why it is particularly important to study WRS in LMICs (e.g., unique stressors, economic pressures) would strengthen the rationale.

Response:

We appreciate the reviewer’s thoughtful suggestion. We have revised the introduction to better articulate why the lack of research on WRS and sleep problems (SP) in LMICs, particularly in Ghana, represents a critical gap. We have indicated in the revised manuscript draft that:

“Crucially, while research has established clear links between occupational stress and sleep quality in formal work settings, the unique challenges faced by informal workers, especially in LMICs, remain understudied. This knowledge gap is crucial, given that LMICs often present unique work-related stressors, including informal employment arrangements, limited labor protections, low wages, high job insecurity, limited access to psychosocial support, and under-resourced health systems [6, 20,21], all of which may exacerbate the effects of WRS on physical and mental health. These contextual differences therefore suggest that findings from high-income countries may not fully capture the lived realities of workers in LMICs, where structural vulnerabilities heighten the risk of cumulative stress and poor sleep outcomes”

3) Please describe any key elements such as the exposure (work-related stress), outcome (sleep problems), and mediators (anxiety, depression) should be more explicitly introduced at the beginning of the Methods section.

Response:

We have revised the opening paragraph of the Methods section to explicitly introduce the key study variables.

4) The total population size or sampling frame is not provided; thus, the representativeness of the sample is unclear. It is not stated whether an official registry or household listing was used to construct the sampling frame, which may raise concerns about selection bias. Please describe them.

Response:

We are happy for this important observation. We have attempted to address the query in the revised manuscript draft. Specifically, we have clarified that prior to data collection, a reconnaissance survey was conducted to identify and enumerate households with active miners. Working in collaboration with local residents and district authorities, we developed a comprehensive household listing that served as the sampling frame. This listing included 1,970 houses.

5) Please describe any potential effect modifiers (e.g., gender, years of mining). Please describe how to assess their effects on clinical outcomes.

Response:

We do appreciate this beautiful idea shared by the reviewer to consider some effect modifiers in our analysis. While we agree with the reviewer based on our understanding on the role of effect medication in proximate relationships, we would humbly like to indicate that the focus on the moderating effect of potential variables falls outside the scope of this paper. We have considered this as the main focus of our other paper which is currently being considered in another destination. We hope that the consolidation of these papers will definitely proffer complementarity to enrich our understanding just as you indicated. However, we have provided a general description of the background characteristics of our study, including gender, age and mining experienced in the discussion section of the revised draft.

6) Please describe cultural and linguistic validity of standardized, validated instruments (PSS-4, PHQ-9, GAD-7, WHODAS 2.0) in the Ghanaian context.

Response:

We have attempted to address this issue in the methods section detailing the cultural and linguistic validity of the standardized instruments used (PSS-4, PHQ-9, GAD-7, and WHODAS 2.0). We have indicated in the revised draft that:

“All measurement tools used in this study (PSS-4, PHQ-9, GAD-7, and WHODAS 2.0) have been previously applied in studies conducted in Ghana [5] or among similar populations in LMICs [16,17], showing acceptable psychometric properties. Where necessary, minor contextual adaptations were made to enhance cultural appropriateness. Instruments were administered in English or translated into Twi using forward and backward translation procedures by bilingual experts. This ensured conceptual and linguistic equivalence. Additionally, the tools were pre-tested among a small group of 25 artisanal miners to ensure clarity, relevance, and cultural sensitivity before full-scale data collection”

7) Communities were purposively selected, possibly limiting generalizability. All data are self-reported; potential recall or reporting biases are not discussed. Residual confounding is not addressed, nor are any strategies (e.g., sensitivity analyses) mentioned to mitigate bias. Please describe those limitations in the discussions section.

Response:

We appreciate these thoughtful comments. We have revised the “Strengths and Limitations” section to explicitly acknowledge the potential limitations arising from the study design, self-reported data, and unmeasured confounders.

8) Please describe the rationale for exceeding the minimum required sample (664 vs. 649).

Response:

In the revised manuscript, we have clarified the rationale for exceeding the minimum required sample size. Although the scientifically estimated minimum sample size was 649 (accounting for a 35% nonresponse rate), we extended data collection to 664 participants to further strengthen the statistical power of the study and account for any unforeseen data quality issues such as incomplete responses or outliers so that we don’t miss our minimum sample target.

9) Please describe any justification for household selection intervals (e.g., every third or fifth household).

Response:

We have provided a clear justification for the use of varying selection intervals. This stratified interval approach was primarily based on community size and housing density to ensure balanced and proportional representation across all selected communities. Additionally, we acknowledge that the term “household” was not the most appropriate and have corrected it to “house(s)” throughout the methods section for clarity. Thank you for the insights.

10) Please describe how to handle missing values (e.g., listwise deletion, imputation).

Response:

Thank you for your insightful comment. We have attempted to address this query by specifying our approach to handling missing data in the statistical analysis section. The section now reads as:

“All analyses were conducted using complete case analysis (listwise deletion), as missing data were minimal (<5%) and determined to be missing completely at random (MCAR) based on Little’s MCAR test”

11) The study draws conclusions about the causal pathway linking WRS → Anxiety → Depression → Sleep Problems, despite being cross-sectional.　The authors should explicitly state that the findings reflect associations rather than causality.

Response:

Thank you for this valuable observation. We agree that the cross-sectional design of the study does not permit causal inference. In response, we have revised the discussion section to explicitly acknowledge that our findings shows associations rather than causality, and have demonstrated potential bidirectionality. The revised draft now reads as follows:

“The observed associations between the study variables may reflect an underlying pathway through which occupational stress is linked to psychological distress and impaired sleep health. However, the cross-sectional nature of this study limits our ability to infer causality or determine the temporal ordering of these variables. It is plausible, for example, that poor sleep may exacerbate depressive or anxiety symptoms, which in turn could increase perceived work stress. Again, individuals already experiencing psychological distress may be more likely to report sleep disturbances. It is well established that chronic sleep disturbances can impair emotional regulation and increase physiological reactivity to stressors, thereby intensifying stress perceptions [47]. Therefore, future longitudinal or experimental research is warranted to test and clarify the directionality of these associations, particularly within the context of small-scale mining.”

12) The discussion lacks acknowledgment of potential unmeasured confounders (e.g., trauma history, shift work, physical illness, work hours). Acknowledge limitations in controlling for all relevant variables that could influence both stress and sleep.

Response:

We appreciate these thoughtful comments. We have revised the “Strengths and Limitations” section to explicitly acknowledge the potential limitations arising from the self-reported data, and unmeasured confounders such as trauma history, shift work, and physical illness.

“Also, reliance on retrospective self-report measures may introduce recall or social desirability biases, due to personal perception, stigma, or misunderstanding of items, potentially affecting the accuracy and strength of the observed associations. Moreover, although we accounted for several covariates, residual confounding from unmeasured factors, such as trauma history, physical illness, work hours, or shift work cannot be ruled out. Furthermore, no sensitivity analyses were conducted to assess the robustness of our findings to potential sources of bias. To improve robustness and generalizability, future research should consider integrating objective assessments of work stress, sleep and mental health, along with more diverse and representative samples across mining communities”

13) Several findings are repeated almost verbatim across multiple paragraphs (e.g., 80% sleep disturbance figure, sequential mediation mechanism). Streamline the discussion to avoid redundancy and enhance clarity.

Response:

We appreciate the reviewer’s observation regarding repetition in the discussion section. In response, we have thoroughly revised the discussion to eliminate redundancy and improve clarity.

14) Despite being conducted in Ghana, there is little reference to Ghana-specific working conditions, healthcare access, or cultural perceptions of stress and sleep. Please discuss how local socioeconomic or cultural factors may shape the findings or their applicability. It is important to discuss them to emphasize the novelty and clinical significance of this study.

Response:

Thank you for this insightful suggestion. In response, we have integrated a new paragraph within the Discussion section that situates our findings within the broader socio-cultural and structural context of small-scale mining in Ghana. The new paragraph reads as follows:

“Moreover, the broader Ghanaian context in which small-scale mining occurs may shape the observed associations. Small-scale miners in Ghana often operate in informal and unregulated settings characterized by hazardous working conditions, long hours, and limited access to healthcare and psychosocial support [56,57]. These conditions may intensify work-related stress and reduce opportunities for seeking help, thereby exacerbating both depression and sleep-related difficulties. Cultural expectations around masculinity and resilience, particularly within mining communities, may also discourage emotional disclosure and reinforce internalization of distress [58,59], contributing to the underreporting of symptoms [75]. Furthermore, the fear of job loss due to periodic government clampdowns on illegal mining activities adds an additional layer of insecurity, which may worsen psychological distress and impair sleep [60,61]. These contextual realities may partly explain the strength of associations observed in this study. As much, highlight the importance of developing interventions that are culturally appropriate, gender-sensitive, and tailored to the unique structural vulnerabilities of this population”

15) Alternative interpretations (e.g., reverse causality where poor sleep leads to perceived stress) are not explored in depth. Please describe alternative hypotheses and how future studies could test them.

Response:

Thank you for this insight. We have now expanded the discussion and have attempted to address this query by including alternative interpretations of the observed associations. The revised draft now reads as follows:

“The observed associations between the study variables may reflect an underlying pathway through which occupational stress is linked to psychological distress and impaired sleep health. However, the cross-sectional nature of this study limits our ability to infer causality or determine the temporal ordering of these variables. It is plausible, for example, that poor sleep may exacerbate depressive or anxiety symptoms, which in turn could increase perceived work stress. Again, individuals already experiencing psychological distress may be more likely to report sleep disturbances. It is well established that chronic sleep disturbances can impair emotional regulation and increase physiological reactivity to stressors, thereby intensifying stress perceptions [47]. Therefore, future longitudinal or experimental research is warranted to test and clarify the directionality of these associations, particularly within the context of small-scale mining”

16) The discussion omits consideration of self-report bias, recall bias, or social desirability bias, which are highly relevant given the constructs measured. Please discuss how the

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