PONE-D-20-21216

Validation of a Commercial Multisensory Sleep Tracker

PLOS ONE

Dear Dr. Mouritzen,

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.

Please note that both reviewers exoressed a series of concerns that must all be addressed.

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We look forward to receiving your revised manuscript.

Kind regards,

Raffaele Ferri, MD

Academic Editor

PLOS ONE

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2. Thank you for including your ethics statement: 'The trial protocol was approved by the Regional Health Research Ethics Committee (SJ-780).'

a. Please amend your current ethics statement to include the full name of the ethics committee/institutional review board(s) that approved your specific study.

b. Once you have amended this/these statement(s) in the Methods section of the manuscript, please add the same text to the “Ethics Statement” field of the submission form (via “Edit Submission”).

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3. Thank you for including your competing interests statement; "The study was based on Garmin Vivosmart 4 sleep tracking because of its multisensory technology and user-friendly design. Garmin kindly borrowed us Garmin watches to perform the experiment. This had no influence on the study design, data collection or analysis, decision to publish, or preparation of the manuscript."

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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: Partly

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

Reviewer #1: Yes

Reviewer #2: N/A

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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: No

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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

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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: This is a validation study for a commercial sleep tracker from Garmin. The study was carried out in parallel with polysomnography, which is the reference standard for sleep recording. A small number of subjects was investigated: 18 healthy persons. One person was recorded for 23 nights, but these were not with polysomnography. The results show that the sleep tracker is good for sleep onset and end of sleep, but not good for sleep stages. This appears to be similar to actigraphy which has not been tested here.

As written in the ‘Polysomnography’ section, I assume that this is not a AASM type I study with supervised polysomnography, but a AASM type II study with polysomnography at home. If this is the case, please state this clearly, because this setting is different to most settings. In type II studies, there is no video recording or no monitoring from an experienced sleep technician. This needs to be noted.

For the smartwatch, you say that it considers not only actigraphy, but PPG as well. But how is this done? Since the results show, that these are comparable to simple actigraphy, may be PPG is not really evaluated? If we consider the WatchPAT device from Itamar as a smartwatch as well, then that device does a better job in evaluationg the PPG signal. Please compare critically.

I am especially interest how the Garmin evaluates REM sleep. That it evaluates REM sleep is only mentioned in brackets in the methods and details are only given when one reads the results. I think this capability of Garmin to detect REM sleep needs to be described in the methods section.

I think it is very good to check for 23 consecutive nights and it is very good to have two devices simultaneously.

As you performed an epoch by epoch comparison, it is of interest, how you arranged for a good synchronization between the polysomnography and the Garmin device. How much was the synchronization error then, less than a second?

The critical summary is appreciated.

Reviewer #2: Authors aimed at evaluating the performance of GV4 against PSG in measuring several sleep parameters in a small sample of 18 “healthy” adults in their home environment. I agree with the authors that the validation of such devices is an important step for adoption. The manuscript is well written.

Comments:

- Please consider the guidelines outlined by Depner at al., 2020 - Wearable Technologies for Developing Sleep and Circadian Biomarkers A Summary of Workshop Discussions

- I would use the term “assessing the performance” instead of “validating”.

- “without sleep disorder”. How sleep disorders were evaluated? Self-report?

- Not sure about having the intra-device reliability as an aim, which has been evaluated on a single participant. What is the generalizability of such results? You may consider this as “exploratory”

- Correlation analysis and interpretation of correlation outputs is misleading. Please remove it.

- “Our results suggest inaccurate sleep stage detection by GV4, but sleep onset and sleep end were accurately detected with few outliers.” The absence of a significant bias between PSG and device does not specifically inform about accuracy/inaccuracy.

- I would not consider low- vs high-frequency HRV as sympathetic vs vagal influence. I would quickly describe the main autonomic changes occurring across stages of sleep.

- It is unclear how the lights-off and lights-on were identified. Participant were asked to press an event-marker button when going to bed. How the authors determined the next morning wake time?

- What was the rate of concordance between the 2 scorers (MHL and TWK)?

- Please provide the data collection time windows (e.g., from Aug 2018 to …)

- Did the authors control for normality of data distribution in the analyses?

- The SD of WASO for GV4 is much lower than the SD of WASO for PSG. Please comment on that.

- Please provide BA plots for all the sleep parameters analyzed

- In the BA plots please use the PSG values on the x axis, and plot the bias or the proportional bias

- EBE should be performed on an individuals’ level. Sensitivity and specificity should be calculated for each participant (night) separately.

- Sensitivity and specificity should be provided for all sleep stages (separately)

- Can you please clarify this statement? “The high agreement in HR and movement detection between devices indicates differences in software rather than hardware”?

- The advantages of incorporating HR and HRV indices by these devices should be due to the sleep stage dependent shifting in autonomic control. Not sure what authors imply with this statement “HRV is influenced by several other conditions than sleep for instance stress level”.

- I would avoid any interpretation about GV4 performance due to the limited generalizability of the results (limitation of the sample used) and the lack of standard in evaluating what could be considered acceptable or not.

- Please check refs. 4, 6, 20 for accuracy

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Reviewer #1: No

Reviewer #2: No

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PONE-D-20-21216R1

Assessing the performance of a commercial multisensory sleep tracker

PLOS ONE

Dear Dr. Mouritzen,

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.

As you can see from the attached comments, one of the reviewers has some remaining concerns that need to be addressed.

Please submit your revised manuscript by Nov 22 2020 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're 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.

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). You should upload this letter as a separate file labeled 'Response to Reviewers'.
• A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'.
• An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'.

If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter. Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter.

If applicable, we recommend that you deposit your laboratory protocols in protocols.io to enhance the reproducibility of your results. Protocols.io assigns your protocol its own identifier (DOI) so that it can be cited independently in the future. For instructions see: http://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols

We look forward to receiving your revised manuscript.

Kind regards,

Raffaele Ferri, MD

Academic Editor

PLOS ONE

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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 #2: (No Response)

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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 #2: Yes

**********

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

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 #2: No

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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 #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 #2: The authors did a nice job in reviewing the paper and replying to the Reviewers’ concerns!

Few additional comments

- I would avoid statements like “Our results suggest inaccurate sleep stage detection by GV4”, etc. There is no standard on what would be considered accurate/inaccurate, and the picture is extremely complex (there are biases, proportional biases, clinical significance other than statistical significance to consider, etc.) . Thus, I believe that statements like that give the readers false interpretation of the device performance.

- In the intro, you may want to mention that PPG-derived HR and HRV has been “validated” against ECG-derived HR and HRV.

- Given the nature of the study you may want to specify which EEG derivation were used.

- I have trouble understanding the sleep onset and sleep end analysis. I usually consider SO the time in which the person falls asleep (the time of the first epoch of sleep after lights-off). Is that the case? What is the PSG event mark?

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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 #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.]

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 PLOS at figures@plos.org. Please note that Supporting Information files do not need this step.

Assessing the performance of a commercial multisensory sleep tracker

PONE-D-20-21216R2

Dear Dr. Mouritzen,

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.

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,

Raffaele Ferri, MD

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

Reviewers' comments: