Objective sleep assessment in >80,000 UK mid-life adults: Associations with sociodemographic characteristics, physical activity and caffeine

Gewei Zhu; Michael Catt; Sophie Cassidy; Mark Birch-Machin; Michael Trenell; Hugo Hiden; Simon Woodman; Kirstie N. Anderson

doi:10.1371/journal.pone.0226220

Peer Review History

Original SubmissionJuly 25, 2019
26 Sep 2019 Decision Letter - yinglin xia, Editor PONE-D-19-20962 Objective sleep assessment in >80,000 UK mid-life adults: associations with sociodemographic characteristics, physical activity and caffeine PLOS ONE Dear Dr. Anderson, Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process. The two reviewers and this editor have identified several strengths of this manuscripts. However this manuscript also exists several weaknesses, especially in statistical analysis. All the comments raised by the two reviewers and this editor should be addressed in the reversion. We would appreciate receiving your revised manuscript by Nov 10 2019 11:59PM. When you are ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file. If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter. To enhance the reproducibility of your results, we recommend that if applicable you deposit your laboratory protocols in protocols.io, where a protocol can be assigned its own identifier (DOI) such that it can be cited independently in the future. For instructions see: http://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols Please include the following items when submitting your revised manuscript: A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). This letter should be uploaded as separate file and labeled 'Response to Reviewers'. A marked-up copy of your manuscript that highlights changes made to the original version. This file should be uploaded as separate file and labeled 'Revised Manuscript with Track Changes'. An unmarked version of your revised paper without tracked changes. This file should be uploaded as separate file and labeled 'Manuscript'. Please note while forming your response, if your article is accepted, you may have the opportunity to make the peer review history publicly available. The record will include editor decision letters (with reviews) and your responses to reviewer comments. If eligible, we will contact you to opt in or out. We look forward to receiving your revised manuscript. Kind regards, yinglin xia, Ph.D. Academic Editor PLOS ONE Journal Requirements: 1. When submitting your revision, we need you to address these additional requirements. Please ensure that your manuscript meets PLOS ONE's style requirements, including those for file naming. The PLOS ONE style templates can be found at http://www.journals.plos.org/plosone/s/file?id=wjVg/PLOSOne_formatting_sample_main_body.pdf and http://www.journals.plos.org/plosone/s/file?id=ba62/PLOSOne_formatting_sample_title_authors_affiliations.pdf 2. We note that you have stated that you will provide repository information for your data at acceptance. Should your manuscript be accepted for publication, we will hold it until you provide the relevant accession numbers or DOIs necessary to access your data. If you wish to make changes to your Data Availability statement, please describe these changes in your cover letter and we will update your Data Availability statement to reflect the information you provide. Additional Editor Comments: This study has the strengths including 1) large data set and 2) using objective measure of sleep. However, this study also has the weaknesses. The most weakness is the statistical analysis. 1. We do not know what exact methods or models were used for this study. 2. z-test is not clear 3. Actually more details of statistical analysis are needed. For example how the continuous variable and categorical variables were analyzed. What tests were used, such as t-test or ANOVA or non-parametric t-test and ANOVA were used? Did the study tested the data distributions? For categorical variables, what tests were used, Chi-square test or Fisher exact test? Did the study use contrast to compare the different levels of categories? 4. Since in the data sets there have several demographics variable such as age and gender, and clinical variables. A statistical model is more appropriate for the analysis instead of simple tests. 5. How many percentage of missing data? Excluding those missing data from the analysis is a limitation. The appropriate approach should include the missing data and using a appropriate method or model to deal with the missing data. [Note: HTML markup is below. Please do not edit.] Reviewers' comments: Reviewer's Responses to Questions Comments to the Author 1. 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 Reviewer #2: Yes ******** 2. Has the statistical analysis been performed appropriately and rigorously? Reviewer #1: I Don't Know Reviewer #2: Yes ****** 3. 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: Yes Reviewer #2: Yes ****** 4. Is the manuscript presented in an intelligible fashion and written in standard English? PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here. Reviewer #1: Yes Reviewer #2: Yes ****** 5. Review Comments to the Author Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters) Reviewer #1: In this study, objective sleep efficiency and duration were investigated by Zhu et al using wrist-worn devices in large cohort of aging 43-79 in UK. It was concluded that shorter sleep duration was associated with male gender, older age, social deprivation and higher caffeine intake. More importantly, the authors found that 6-7 hours sleep/night was associated with the highest physical activity level, and discussed the differences between objective assessment and subjective questionnaire. Minors: It is impossible to include participants aged <43 for the current study. Letters denoting column proportion z-test in note of Table 1 are confusing, better if authors can explain them more. Line 174-320: duplicate reference Line 166-174: font and size need to edit Line 84: “the oldest old”? Line 56: “difficulties” in? Line 93: age “40-69”; line 31: aged “43-69”? Line 166-168: compared to what? Refer to Fig 1 or Table 1? Line 330: gender p-value: p < 0.001 in table 2. Reviewer #2: The authors assessed a relationship between sociodemographics and sleep duration determined by objective actigraphy measures in a large population based sample and showed relevant factors to sleep duration. Also the authors the demonstrated inverse U-shaped relationship between sleep duration and physical activity by objective sleep measures. Introduction and methods section are clear and well written. Page 9-16, lines 166-320, Large font texts and references list are incorrectly inserted here. Please check and correct them. Are there any correlations between sleep time, measured by objective measures, and subjective sleepiness or sleep complaints? Can actigraphy differentiate sleep and immobile waking state? Information about smoking and alcohol intake can interfere with sleep and should be presented if possible. Statistical analysis should be described in more detail, as this study address a large sample. ****** 6. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files. If you choose “no”, your identity will remain anonymous but your review may still be made public. Do you want your identity to be public for this peer review?** For information about this choice, including consent withdrawal, please see our Privacy Policy. Reviewer #1: Yes: Guo Luo Reviewer #2: No [NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files to be viewed.] While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email us at figures@plos.org. Please note that Supporting Information files do not need this step. https://doi.org/10.1371/journal.pone.0226220.r001
Revision 1
14 Oct 2019 Author Response Objective sleep assessment in >80,000 UK mid-life adults: associations with sociodemographic characteristics, physical activity and caffeine. PONE-D-19-20962 Dear Dr Yinglin Xia, We would like thank the reviewer for their time and helpful comments. Amendments to the original text can be identified using track. Please find our responses to the comments as follows. Editor comments: 1. No statistical model was previously carried out. Additional explanation on the statistical tests used are added in the method section. 2. More explanation on the z-test are added – z-test was used instead of standard t-test to determine whether 2 population mean was different because of the large sample size in the current study. 3. Details of the statistically analysis are now added as requested – Monte carlo method with 99% confidence level was used to estimate the exact significant level. ANOVA was used on continuous variables and Chi-square test was used on categorical variables. Kolmogorov-smirnov test indicates that sleep duration does not follow a normal distribution (D(84411)=0.065, p<0.001). 4. Statistical model results are added as suggested. 5. 11.6% (n=10918) were excluded from the current study including 1.6% (n=1425) due to participant drop-outs over-time. Comparison between the population in the current study and those excluded was undertaken, there are no significant differences in terms of age and gender, and therefore we believe that there is unlikely to be a selection bias. Reviewer 1 comments: Letters denoting column proportion z-test in note of Table 1 are confusing, better if authors can explain them more. Additional explanation is added in the method section as suggested. Line 174-320: duplicate reference This might be an error in printing from Microsoft word. When viewing on the computer or print from PDF, this problem does not occur. Line 166-174: font and size need to edit This might be an error in printing from Microsoft word. When viewing on the computer or print from PDF, this problem does not occur. Line 84: “the oldest old”? This refers to the 85+ population. Line 56: “Difficulties” in? This refers to difficulties in initiating and maintaining sleep. The sentence has been amended to make it clearer. Line 93: age “40-69”; line 31: aged “43-69”? There is a time lag between self-reported data and accelerometry data. Participants were aged 40-69 years during in baseline assessment around 2007-2010, but their age are between 43-79 years when accelerometry data were taken around 2013-2015. Line 166-168: compared to what? Refer to Fig 1 or Table? This sentence has now been rearranged to improve clarity. Line 330: gender p-value: p<0.001 in table 2 This typo has now been changed. Reviewer 2 comments: Page 9-16, lines 166-320, large font texts and references list are incorrectly inserted here. Please check and correct them. This might be an error in printing from Microsoft word. When viewing on the computer or print from PDF, this problem does not occur. Are there any correlations between sleep time, measured by objective measures, and subjective sleepiness or sleep complaints? A previous study by Chaput JP et al. (2013) found a ‘U-shaped’ association between subjective sleep duration and metabolic measures and the current study found a similar association between that and objective sleep duration. Can actigraphy differentiate sleep and immobile waking state? Vincent T. van Hees et al. (2015) found that GGIR over-estimates sleep duration by 31 minutes with 83% accuracy. If arm angle does not change greater than 5 degrees in 5 minutes then it is considered a bout of sleep. Therefore actigraphy remains an acceptable tool to estimate the major sleep period, widely used across a number of different population cohort studies. Information about smoking and alcohol intake can interfere with sleep and should be presented if possible. Smoking status and alcohol intake information are available, but due to the ~5 years’ time lag between these data and accelerometry data, smoking and alcohol data is not presented in this paper. Statistical analysis should be described in more details, as this study address a large sample. More information on the statistical tests are added in the method section as suggested. Yours sincerely Miss Gewei Zhu and Dr Kirstie Anderson Attachments Attachment Submitted filename: Editor comments and responses.docx https://doi.org/10.1371/journal.pone.0226220.r002
29 Oct 2019 Decision Letter - yinglin xia, Editor PONE-D-19-20962R1 Objective sleep assessment in >80,000 UK mid-life adults: associations with sociodemographic characteristics, physical activity and caffeine PLOS ONE Dear Miss Gewei Zhu and Dr Kirstie Anderson, Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process. Since the Kolmogorov-smirnov test indicates that sleep duration does not follow a normal distribution (D(84411)=0.065, p<0.001), the non-parametric Kruskal-Wallis ANOVA should be used.The study must re-analyze this part. We would appreciate receiving your revised manuscript by Dec 13 2019 11:59PM. When you are ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file. If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter. To enhance the reproducibility of your results, we recommend that if applicable you deposit your laboratory protocols in protocols.io, where a protocol can be assigned its own identifier (DOI) such that it can be cited independently in the future. For instructions see: http://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols Please include the following items when submitting your revised manuscript: A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). This letter should be uploaded as separate file and labeled 'Response to Reviewers'. A marked-up copy of your manuscript that highlights changes made to the original version. This file should be uploaded as separate file and labeled 'Revised Manuscript with Track Changes'. An unmarked version of your revised paper without tracked changes. This file should be uploaded as separate file and labeled 'Manuscript'. Please note while forming your response, if your article is accepted, you may have the opportunity to make the peer review history publicly available. The record will include editor decision letters (with reviews) and your responses to reviewer comments. If eligible, we will contact you to opt in or out. We look forward to receiving your revised manuscript. Kind regards, yinglin xia, Ph.D. Academic Editor PLOS ONE [Note: HTML markup is below. Please do not edit.] Reviewers' comments: Reviewer's Responses to Questions Comments to the Author 1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation. Reviewer #1: (No Response) Reviewer #2: All comments have been addressed ******** 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: (No Response) Reviewer #2: Yes ****** 3. Has the statistical analysis been performed appropriately and rigorously? Reviewer #1: (No Response) Reviewer #2: N/A ****** 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 Response) Reviewer #2: Yes ****** 5. Is the manuscript presented in an intelligible fashion and written in standard English? PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here. Reviewer #1: (No Response) Reviewer #2: Yes ****** 6. Review Comments to the Author Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters) Reviewer #1: (No Response) Reviewer #2: The authors have well addressed my concerns. Page 9-16, lines 166-320, large font texts and references list are incorrectly inserted here. Please check and correct them. However, this has not been revised. Can the authors check PDF version of the manuscript before submission? ****** 7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files. If you choose “no”, your identity will remain anonymous but your review may still be made public. Do you want your identity to be public for this peer review?** For information about this choice, including consent withdrawal, please see our Privacy Policy. Reviewer #1: No Reviewer #2: Yes: Keisuke Suzuki [NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files to be viewed.] While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email us at figures@plos.org. Please note that Supporting Information files do not need this step. https://doi.org/10.1371/journal.pone.0226220.r003
Revision 2
19 Nov 2019 Author Response Dear Yinglin Xia, We would like thank the reviewer for their time and helpful comments. Amendments to the original text can be identified using track. Please find our responses to the comments as follows. Comment: Since the Kolmogorov-smirnov test indicates that sleep duration does not follow a normal distribution (D(84411)=0.065, p<0.001), the non-parametric Kruskal-Wallis ANOVA should be used. The study must re-analyze this part. Response: Analysis between continuous variables has been repeated using the Kruskal-Wallis test. Method and results section has been amended. Largely results were unchanged but all amendments are clearly marked. Reviewer comments to the author Reviewer 2: Page 9-16, lines 166-320, large font texts and references list are incorrectly inserted here. Please check and correct them. However, this has not been revised. Can the authors check PDF version of the manuscript before submission? Response: No error in font size and reference list are detected on either of our computers, therefore we are unsure whether this is due to errors when uploading online. Yours sincerely Miss Gewei Zhu and Dr Kirstie Anderson https://doi.org/10.1371/journal.pone.0226220.r004
22 Nov 2019 Decision Letter - yinglin xia, Editor Objective sleep assessment in >80,000 UK mid-life adults: associations with sociodemographic characteristics, physical activity and caffeine PONE-D-19-20962R2 Dear Dr. Anderson, We are pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it complies with all outstanding technical requirements. Within one week, you will receive an e-mail containing information on the amendments required prior to publication. When all required modifications have been addressed, you will receive a formal acceptance letter and your manuscript will proceed to our production department and be scheduled for publication. Shortly after the formal acceptance letter is sent, an invoice for payment will follow. To ensure an efficient production and billing process, please log into Editorial Manager at https://www.editorialmanager.com/pone/, click the "Update My Information" link at the top of the page, and update your user information. If you have any billing related questions, please contact our Author Billing department directly at authorbilling@plos.org. If your institution or institutions have a press office, please notify them about your upcoming paper to enable them to help maximize its impact. If they will be preparing press materials for this manuscript, you must inform our press team as soon as possible and no later than 48 hours after receiving the formal acceptance. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org. With kind regards, yinglin xia, Ph.D. Academic Editor PLOS ONE Additional Editor Comments (optional): Reviewers' comments: https://doi.org/10.1371/journal.pone.0226220.r005
Formally Accepted
18 Dec 2019 Acceptance Letter - yinglin xia, Editor PONE-D-19-20962R2 Objective sleep assessment in >80,000 UK mid-life adults: associations with sociodemographic characteristics, physical activity and caffeine Dear Dr. Anderson: I am pleased to inform you that your manuscript has been deemed suitable for publication in PLOS ONE. Congratulations! Your manuscript is now with our production department. If your institution or institutions have a press office, please notify them about your upcoming paper at this point, to enable them to help maximize its impact. If they will be preparing press materials for this manuscript, please inform our press team within the next 48 hours. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information please contact onepress@plos.org. For any other questions or concerns, please email plosone@plos.org. Thank you for submitting your work to PLOS ONE. With kind regards, PLOS ONE Editorial Office Staff on behalf of Dr. yinglin xia Academic Editor PLOS ONE https://doi.org/10.1371/journal.pone.0226220.r006

Open letter on the publication of peer review reports

PLOS recognizes the benefits of transparency in the peer review process. Therefore, we enable the publication of all of the content of peer review and author responses alongside final, published articles. Reviewers remain anonymous, unless they choose to reveal their names.

We encourage other journals to join us in this initiative. We hope that our action inspires the community, including researchers, research funders, and research institutions, to recognize the benefits of published peer review reports for all parts of the research system.

Learn more at ASAPbio .