Review History


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Summary

  • The initial submission of this article was received on December 20th, 2013 and was peer-reviewed by 4 reviewers and the Academic Editor.
  • The Academic Editor made their initial decision on January 28th, 2014.
  • The first revision was submitted on January 31st, 2014 and was reviewed by 4 reviewers and the Academic Editor.
  • A further revision was submitted on March 11th, 2014 and was reviewed by 2 reviewers and the Academic Editor.
  • A further revision was submitted on March 21st, 2014 and was reviewed by the Academic Editor.
  • A further revision was submitted on March 21st, 2014 and was reviewed by 1 reviewer and the Academic Editor.
  • The article was Accepted by the Academic Editor on March 25th, 2014.

Version 0.5 (accepted)

· · Academic Editor

Accept

Dear Authors, Thank you for your revised manuscript which has been accepted for publication after final peer review.

Reviewer 3 ·

Basic reporting

No comments

Experimental design

No comments

Validity of the findings

No comments

Comments for the author

Overall, the article is very much improved.

Version 0.4

· · Academic Editor

Minor Revisions

Dear Authors,

As the editor responsible for the quality of the article and after reading your explanation, and your offer to defer to the Editor on this issue, I on behalf of Peer J request you to follow the comments of the peer reviewer that is 1.1.

Overall, the readability of this draft is much improved but there remains significant concern with the data in table 1 (it STILL does not make sense). The authors did not incorporate any of the changes to Table 1 that were recommended by this reviewer. For example, the column header missing, for example - 80% of urban studies were missing? This reviewer recommends reorganizing your table entirely.

Please proceed to revise the Table according to the request of the journal and the reviewer as soon as possible.

Thanking You.

Jafri Abdullah
Academic Editor

Version 0.3

· · Academic Editor

Minor Revisions

Dear Authors,There are still revisions to be made to your manuscript before it can be acceptable. Please revise the sections and Tables that are needed to make it into a citable manuscript.

·

Basic reporting

No Comments

Experimental design

No Comments

Validity of the findings

No Comments

Comments for the author

No Comments

Reviewer 3 ·

Basic reporting

No comment

Experimental design

No comment

Validity of the findings

No comment

Comments for the author

2.1. Overall, the readability of this draft is much improved but there remains significant concern with the data in table 1 (it STILL does not make sense). The authors did not incorporate any of the changes to Table 1 that were recommended by this reviewer. For example, The column header missing, for example - 80% of urban studies were missing? This reviewer recommends reorganizing your table entirely.

It is understood that the differences in weekday and weekend sleep duration is similar between urban and rural areas. However, it does appear that urban, in general (over weekend and weekdays combined) sleep less. I would add that to the results and discussion.

Version 0.2

· · Academic Editor

Minor Revisions

Dear Authors,Please revise your manuscript according to the comments of the peer reviewers especially peer reviewer 3 who has very important comments to make your manuscript cit-able in the long run.The manuscript will be re-reviewed after corrections.

·

Basic reporting

Abstract

1- “A total of 12, 424 subjects...” isn’t better than “A total of 12, 424 observations...”?

2- In the sentence: “Regarding urban and rural areas, a much higher proportion of short-sleep (92%) was observed in the former”, the authors should also specify the proportion of short sleepers in rural areas.

3- What are the keywords?

Experimental design

Methods

1- Line 80 = in “…water source;”, the authors should change the “;” to “,”

2- Line 91-92 = Maybe this sentence would be better like this: “…de Estadística e Informática, 2010). Vacations in Peru, in particular school vacations, are from January to March; so, the time of when the survey was conducted did not match our vacations”.


Results

1- Line 163 = The correct sentence isn’t “Given THE similar…”

2- Line 170-171 = The percentage of urban short-sleep in this sentence “Regarding urban and rural areas, a much higher proportion of short-sleep was observed in the former: 5.2% (95% CI 3.8%-7.0%) for urban and 1.4 (95% CI 1.0%-2.1%) for rural areas”, seems to be incompatible with the one from this Abstract sentence “Regarding urban and rural areas, a much higher proportion of short-sleep (92%) was observed in the former”.

3- Line 176 = “… became closer TO 1”

4- Line 177 = “Table 3”

Validity of the findings

Discussion

1- Line 194 = “mirror pattern”

2- Line 223-224 = “Krueger & Friedman (2009)”

3- Line 281-283 = Maybe the sentence is better like this: “In our case, urban settings presented a higher frequency of short sleep duration comparing with rural settings, possibly because of the different economical activities and lifestyle patterns between these two settings.”

Reviewer 2 ·

Basic reporting

No comments

Experimental design

No comment

Validity of the findings

No comment

Comments for the author

Ok

Reviewer 3 ·

Basic reporting

The authors incorporated some of the recommendations from this author's previous review. Overall, the readability of this draft is improved but there remains significant concern with the data in table 1 (it does not make sense). The authors did not incorporate any of the changes to Table 1 that were recommended by this reviewer.

For example, the authors state that 92.0% of the urban population is classified as "short sleep". I strongly recommend re-organizing your table data to enhance clarity.

This reviewer is also still concerned with the reporting of adolescent data. Please present the data (so variability can be seen) for adolescents and adults separately (table and text). Second, .25 hours is not equal to 30 minutes ("our definition is 25 minutes short..."), it is equal to 15 minutes.

This author is also still concerned with the representation of "urban" vs. "rural" findings, something you highlight in your rationale as an import reason for doing this study "developing country" and something you list as a "main finding" "There was five times more short sleep in urban areas".. It is well-documented that weekday and weekend sleep differ remarkably for weekday vs. weekend sleep in developed countries. You dropped day-of-the-week out of your analyses and did not present day-of-week data for urban vs. rural. Please provide this data.

Experimental design

no comments

Validity of the findings

See above comments w/ regard to tabular representation of data as well as age-related and day-of-week finding across area (urban vs. rural).

This reviewer feels very strongly that these issues be addressed.

Comments for the author

See above comments w/ regard to tabular representation of data as well as age-related and day-of-week finding across area (urban vs. rural).

This reviewer feels very strongly that these issues be addressed.

Reviewer 4 ·

Basic reporting

No comments

Experimental design

No comments

Validity of the findings

No comments

Comments for the author

The author has made the necessary changes as per recommended by the reviewers.

Version 0.1 (original submission)

· · Academic Editor

Major Revisions

Dear Authors,There are 3 out of the 4 reviews of your manuscript with good suggestions to improve your manuscript's quality.I hope you can do this so as it can be re-reviewed by the same reviewers as soon as possible.

Reviewer 1 ·

Basic reporting

Summary:
This is a large (12,424) cross-sectional study aiming to describe the occurrence of short and long sleep duration in a large, representative sample of adult and adolescent Peruvian's. Data are stratified across socio-demographic variables and development (urban vs. rural). These data are fairly novel as limited data are available on sleep habits of Latinos in rural regions of the world. The aim is to quantify short and long sleeping duration as it may be a potential modifiable risk factor as it relates to all-cause mortality.

Overall assessment: This manuscript does add to the science regarding cross-cultural aspects of sleep. However, overall the amount of text can be reduced and the clarity of each sentence could be enhanced. The largest finding in this study seems to be the difference in sleep duration across urban and rural populations. The conclusions need to support this. Second, the hypotheses w/ regard to urban vs. rural and age/developmental changes (adolescence) needs to be stated and presented in the results. Age-related changes need to be presented if that is an aim (which I suspect it to be).

Experimental design

Sleep duration data were garnered cross-sectionally from 12,424 particiapants using a single-item question of habitual (across past week) sleep duration on weekdays and weekends. Clarification needed on points listed below.

Validity of the findings

Introduction Specific
line 24- What is "inappropriate" sleep duration? I would suggest "inadequate".
line 24- inadequate sleep duration is associated w/ a variety of cognitive, emotional, behavioral, and metabolic consequences. Not just cardiovascular disease. I suggest a more broad encapsulation.
line 40- clarify context specific
line 41- Define NCD
lines 44... I suggest being more broad w/ known consequences of short sleep. Road injuries and accidents are unlikely to be a major concern in rural areas?

Methods specific
Comments:
1. It is unclear how "rural" vs. urban was determined. Ex. "was many walls and access to water?" Please clarify
2. Was napping assessed? This is a crucial piece of information, especially in light of this 'siesta' culture.

Results specific
General-Please add sleep durations for adolescent sub-sample (age 12-19 as per table 1) as well as data for napping (if available)
line 165- Please explain "All point estimates became attenuated following adjustment"? Adjustment for what?
line 180- I would suggest removing the word "appropriate". No one knows what appropriate sleep is. I would say something like "Peruvians self-reported sleep duration is similar to recommended values from ..."
line 198-99- How do these studies define short sleep?
Table 1- You can remove "missing" column. Missing data can be inferred from complete %.
Table 2- The % do not add up. Ex. 92.0% of urban have short sleep, but 79.4% have regular sleep? The entire table needs clarification. Also, it is unclear why comparisons are made between short and regular sleepers as opposed to the categorical variable of interest (ex. short sleep in urban vs. rural). This would be the most consistent w/ your objectives.
Table 3. I would like to see the table footnote list all control variables. Why is the adolescent sub-sample the control? These data are not explained in the results.
Conclusions- please integrate information from the adolescent sample as well as bolster the interpretation of why rural and urban Peruvians sleep differently.

Limitations- Add napping if you did not assess.

Comments for the author

This manuscript does add to the science regarding cross-cultural aspects of sleep. However, overall there are substantial concerns regarding overall clarity of the manuscript. Much attention is needed in the results section and tabular display of data.

Reviewer 2 ·

Basic reporting

The manuscript was generally well written, has a clear flow, and grammatically correct. All the contents in the sections were presented well.

Experimental design

The experimental design was well-planned, of high technical standard and relevant to the aims of the study.

Validity of the findings

The tables, results and discussion were presented in an orderly manner.

Comments for the author

In Table 2, column 'regular sleep', 'n=' is left out.

·

Basic reporting

Good

Experimental design

No comment

Validity of the findings

No comment

Comments for the author

over all, the manuscript is good, but it would be better if the differences between some variables that have p value < 0.05 were analyzed, such as: education, age, area, assets index, etc.

·

Basic reporting

Abstract

1. Avoid passive voice, such as “were used” or “were included”.

2. Characterize the population and variables in the beginning of the methods:

After “The aim of this study was to explore the patterns of sleep duration in the Peruvian adult and adolescent population, together with its socio-demographic profile.”

Insert “A total of 12,424 observations, mean age 35.8 years (SD ±17.7), 50.6% males, were included in the analysis.”

3. Define the variables earlier:

After “describe sleep duration according to socio-demographic variables”, define which are these variables.

4. When the authors wrote that subjects sleep during the weekdays almost the same than during the weekend, can I conclude that they are not sleep-deprived duo to work during weekdays?

5. After “Regarding urban and rural areas, a much higher proportion…” define how much higher is this.

6. After “On the multivariable analysis…”, define which variables were included in this analysis.

7. When the authors wrote that “short-sleepers were twice more likely to be older and to have higher educational status, and 50% more likely to be currently employed. Similarly, relative to regular-sleep, long-sleepers were more likely to have a lower socioeconomic status as per educational attainment.”

I thought that these are the patterns associated with urban and rural areas, independently on how they sleep – Am I correct?

- Urban = older, higher educational status, employed
- Rural = lower socioeconomic status

8. Key-words aren’t necessary?


Introduction

1. Line 19 = I didn’t like the construction of this phrase: “Over the last decades, sleep duration has changed leading to people sleeping less or more than they used to.”

What about: "Over the last decades, sleep duration has changed: people are sleeping less (or more) than they used to.”

Also about this sentence, why is this happening? I suggest the authors briefly discuss this on Introduction and deeply on the Discussion.

2. Line 20 = When the authors wrote “ten industrialized countries”, define which ones.

3. Line 21 = “that long-sleep duration, over nine hours, was more prevalent (Bin et al. 2013)”. In this sense, shouldn't nine hours be considered as the normal (and physiologic) sleep duration pattern? Maybe this issue deserves to be raised in the Discussion.

4. Line 23 = When the authors wrote “seven countries” or “six countries”, define which ones.

5. Line 24 = “deficit” isn’t better than “defect”?

6. Line 25 = The authors wrote “non-communicable diseases” but used “NCDs” on line 41. Thus insert NCD after “non-communicable diseases” of line 25.

7. Line 25 = from “A meta-analysis…” until the end of line 32, I thought a bit complex text, thus I have a suggestion to become simpler:

Both short and long sleep durations: 1- are a risk factor for dying of coronary heart disease or stroke (Cappuccio et al. 2011), 2- associate with type-2 diabetes (Cappuccio et al. 2010a), 3- have positive association with obesity (Marshall et al. 2008), 4- increase risk of mortality (Cappuccio et al. 2010b; Gallicchio & Kalesan 2009). Yet, results are still inconclusive on this matter (Kurina et al. 2013).

8. Line 35 = the authors wrote the acronym LAC only 3 times in the whole MS. Maybe is better not to use it. If it is to use one acronym, I suggest SD for sleep duration.

9. Line 38 = which are these results of Olds et al. 2010? I suggest the authors describe it.

10. Line 43-47 = I did not like the construction of this phrase, thus I suggest this:

Second, another context-specific characteristic from our sample is the road traffic injuries that are linked to tiredness or sleepiness (Rey de Castro & Rosales-Mayor 2010), which is a very common feature among Lima’s public transportation drivers (Risco et al. 2013). Thus, having a broader picture at the population-level of sleeping-related factors would inform the potential burden of this public health problem.

Experimental design

Methods

1. Avoid passive voice on lines = 71, 76, 85, 115, 122,124,128, 131, 133

2. Line 67 = why for the primary units is “sample”, and for the secondary units is “sampling”?

3. Line 75 = when the authors wrote “elsewhere”, define where is it.

4. Line 87 = when the authors describe when the survey was conducted, is this considered vacation times? At least in part of the time? And for students? Maybe it deserves a discussion.

5. Line 105 = Maybe the sentence “as in this calculation” should be deleted for the phrase become clearer.

6. Lin 133 = For the p < 0.05, Isn't necessary a Bonferroni correction for the number of comparisons?


Results

1. Line 141-142 = What is the final sample? I suggest the authors describe it.

2. Line 143-144 = Describe where is the significant difference, for example: “in the missing data, males were prevalent”.

3. Line 153-154 = A statistical test was performed to be sure that both distributions are not significantly different?

4. Line 166-167 = Why not gender (male and female) and area (rural or urban) were also variables to be associated with sleep duration?

Validity of the findings

Discussion

1. Line 181-182 = This similarity of the sleep duration in weekdays and weekends could be interpreted as if subjects are sleeping qualitatively well during working weekdays, then they don't need to sleep more during weekends to compensate? Maybe this is an interesting issue to be discussed.

2. Line 200-204 = Why these countries have more short-sleepers and less long sleeper than Peru? Are there cultural and/or economic effects involved? I believe is important to discuss it.

3. Line 207 = As commented before in the Methods, the data was collected in the end of the year, thus it could be on a vacation period, which could have biased the results. I believe this is important to be discussed.

4. Line 217-220 = Are there similar studies on socio-demographic variables such as employment and education of short and long sleepers in developing countries?

5. Line 221 = Maybe another limitation is: how to evaluate sleep quality? Because some people naturally sleep less than 6 hours, and for them this is enough to stay well during the whole day.

6. Line 242-243 = I did not like this phrase “and this could be particularly sensitive with sleep duration provided a policy could be seen as a restriction in anyone’s free use of time.”

I suggest: “and this could be particularly difficult since providing a sleep duration policy could be seen as a restriction in anyone’s freedom to use their time.” – Is this idea the authors want to transmit?

7. Line 246 = write “NCD” instead of non-communicable diseases. Actually, since NCD was written only three times in the whole MS, maybe is better not to use this acronym.

8. Line 266-267 = I suggest the authors to write "- or long sleep duration - e.g. people with no formal education or just having completed high school."

Comments for the author

This MS is very important for the area of sleep research, especially on sleep duration among Latin American countries, thus I believe it should be accepted. However, I believe the MS can be improved with a major review.

Nevertheless, please note that my review consists only in suggestions (rather than mandatory changes), thus feel free to accept it or not. I believe my suggestions will improve the quality of the MS, but if you do not accept some of them, please let me know why, so I can also learn with this experience.

In some sentences, I could understand what the authors wrote, but I believe it could be better written. However, since I am not a natural English speaker, I could be wrong.

I also have some doubts/questions on the MS, such as: a) items 4, 7 and 8 of Abstract; b) item 4 of Results and c) item 1 of Discussion. I appreciate if the authors could answer me those questions.

I also attached the original PDF file of the MS, in which I highlighted and commented the points I believe should be reviewed.

All the best and good luck!

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