PONE-D-21-02910Persistence of sleep difficulties over 16 years amongst 66,948 working-aged adultsPLOS ONE

Dear Dr. Saltychev,

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Have the authors made all data underlying the findings in their manuscript fully available?

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Reviewer: No

Review Comments to the Author

This manuscript examined longitudinal sleep difficulties of adults in Finland. This is the first study to prospectively assess sleep and modifiable health factors in a cohort of adults longitudinally over 2.5 decades. The authors report that sleep difficulties are persistent across the 16 year assessment period. They found specific health factors to be associated with sleep depending upon characteristics of age and sex. A strength of the study is the longitudinal cohort design allowing for repeated measurement and within subjects comparison. The primary weakness of the manuscript are grammatical/spelling/punctuation errors throughout the document that should be addressed for clarity and to improve readability. Additionally, the manuscript would benefit from further description of the manner in which the analyses were conducted with this specific sample in addition to the general description of the analytic techniques that were used. To summarize, this is an interesting research question and a unique population that provides new insights into the relationships between sleep and modifiable health outcomes. Thank you for the opportunity to review this paper.

Abstract and Statement of Significance

1. There are several grammatical errors in the Abstract and the Statement of Significance (e.g. words such as “a” and “the” appear to be missing resulting in some incomplete sentences and impaired readability, the phrase “solely depending” should be changed to “Solely dependent”). These section would benefit from a more thorough review by the authors. The Statement of Significance repeats the last line of the Abstract verbatim and does not explain the significance of this work (e.g. how does this work expand on what is already known about sleep difficulties in adults?).

Introduction

2. There are grammatical errors throughout the Introduction section (as in the Abstract, words such as “a” and “the” appear to be missing; e.g. lines 76-77). Some sentences are awkwardly worded such that readability is impacted (e.g. line 77-78)

Methods

1. There are grammatical errors throughout the Methods section (as in the Abstract, words such as “upon”; e.g. line 122)

2. The Methods section would benefit from a review for errant punctuation and general grammatical/spelling errors (e.g. line 104-10).

3. There is no description of whether informed consent (or a waiver alternative) was obtained from participants.

4. How were physical activity and alcohol consumption dichotomous values determined? If this is based on established norms, citations should be included. Additionally, it might be more accurate to use different cut offs for excessive alcohol consumption based on participant characteristics (e.g. sex or BMI).

5. There is no citation or description or established psychometric properties of the Jenkins Sleep Scale, nor is there a citation for the method for handling missing data.

6. After introducing the JSS abbreviation, Continue to use it through out rather than switching back and forth between the abbreviation and spelling out the full name of the measure in the text.

7. What methods or variables were used to determine the six clusters? What do the clusters consist of? How are they similar or different?

Results

8. It is unclear to me how the cluster models/trajectories (shown in Table 1) relate to the risk factor analyses (shown in Table 2). Further description of the purpose of and relationship between these analyses in either the Methods/Statistical Analysis section or in the Results would be helpful. Discussion

Discussion

9. There are grammatical errors throughout the Discussion section (e.g. lines 166-167, line 174, line 175, line 177, lines 181-183, line 198).

10. Line 178 – The term “instrument” should be replaced with a more accurate term such as “technique,” as the analysis is not physical tool or device as is suggested by the term instrument.

11. Line 201 – change “may” to “should”

Tables and Figures

12. Table 1: the text “The chosen models are shown in bold” belongs in the footnote/caption rather than in the title.

13. Table 2: the text “Two trajectories with lowest baseline JSS scores were combined into one cluster (“steadily good sleepers”) and used as a reference” belongs in the footnote/caption rather than in the title. Additionally, highlighting significant findings in some manner (e.g. bolding text) would be helpful to the reader.

14. The line graph Figures are completely unreadable as the text is blurry.

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Persistence of sleep difficulties for over 16 years amongst 66,948 working-aged adults

PONE-D-21-02910R1

Dear Dr. Saltychev,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

As suggeste by a reviewer, in editing, the text "% confidence limits are shown as dot-lines" in the Results section in reference to the placement of Figure 1 appears to not have been removed with the rest of a phrase that was deleted from this revised version of the manuscript. This may need to be removed/clarified. 

Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication.

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Kind regards,

Federica Provini

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

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Reviewer #1: All comments have been addressed

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2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

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3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

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4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: No

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5. Is the manuscript presented in an intelligible fashion and written in standard English?

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Reviewer #1: Yes

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6. Review Comments to the Author

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Reviewer #1: I thank the authors for their attention to previous comments and for the opportunity to review this interesting research. In editing, the text "% confidence limits are shown as dot-lines" in the Results section in reference to the placement of Figure 1 appears to not have been removed with the rest of a phrase that was deleted from this revised version of the manuscript. This may need to be removed/clarified.

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Reviewer #1: No