Microbiota Composition and Probiotics Supplementations on Sleep Quality—A Systematic Review and Meta-Analysis

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This systematic review and meta-analytic study had two goals:

i) to evaluate differences in GM composition between subjects with sleep disturbances versus healthy controls with α­diversity index as the primary endpoint- 4 studies detected for meta-analysis

ii) to investigate the effectiveness of probiotics to treat sleep disorders with PSQI and ESS as the primary endpoint

Meta-analysis for first aim did not find any significant difference between g α­diversity of GM while meta-analyisis for second aim found that probiotic consumption significantly reduced PSQI score compared to placebo administration

The major limitation of this study of is high heterogenety of the study parameters which makes results hard to summarized, however drawbacks of the study are clearly and thorougly clearly stated in the discussion.

 

The only objection is regarding ESS explanation in discussion which is only partially correct

ESS is questionnaire to assess primarily day time sleepiness. Self assessed propensity to fall asleep is indeed assessed by ESS but in context of being sleepy, not being insomnic. Please clarify.

Author Response

Thank you for your observation. We revised this part of the discussion, according to your and reviewer 2 suggestions.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

This is an interesting paper on a complex and important topic. It is well done and is useful to the field mainly to highlight the need for more precise and well-designed studies. A discrepancy between the text and Figure Three in the Results section needs to be corrected, otherwise only minor revisions are suggested for clarification and grammar.  The authors could provide a little more clarification on the difference between alpha and beta measures of microbiome composition for readers unfamiliar with those concepts, since it is a review article aimed at a broad audience.

ABSTRACT

Line 16: change “highlighted” to “highlight”

Line 17: change “the condition” to “this condition”

Line 18: change “apparently in contrast” to “inconsistent”

Line 20: replace “January 2022 and July 2022” to the range of years covered by the review

Line 25: change “No different “ to “No difference in”

Line 26: change “In conclusion, while…” to “While…”

Line 26: change “could not be” to “is not”

INTRODUCTION

Line 44-45: change “reflect of” to “lead to”

Line 48: The authors might further clarify the difference between alpha and beta measures of microbiome composition for the non-expert reader. Is this describing phylogenetic variation within individual gut microbiomes relative to variation among individuals? What about among studies or between treatment groups? The sense in which “communities” is used here isn’t exactly clear with respect to the alpha-beta terminology.

Line 52: change “also” to “additional”

Line 85: change “is matter” to “is a matter”

Line 86: Why is “the possible beneficial impact of probiotics in sleep disorders a matter of debate”? Another sentence here would help.

MATERIALS AND METHODS

Lines 91-92: change “indications collected in” to “criteria described”

Line 93: change “carried bout until July” to “carried out from (insert beginning date) until July 2022” to indicate from when to July 2022?

Line 114: change “conducted independently” to “independently conducted”

Line 121: change “patients” to “patient’s”

Line 145: change “by” to “using”

Line 146: delete “was used for statistical analysis”

RESULTS

Figure 1, Meta-analysis1: change “throughtitle” to “by title”

Figure 1, Meta-analysis2: change “throughtitle” to “by title”

Figure 1, Meta-analysis1, Records excluded: change “reviewarticles” to “review articles”

Figure 1, Meta-anlaysis1, Full text articles excluded: change “alterated” to “altered”, and “lacking of the analysis” to “lacking analysis”

Line 8: change “while five” to “and five”

Line 13: change “Compliance to supplementation” to “Compliance with supplementation protocols”

Line 15: delete “also in this second analysis”

Line 17: change “compliance to” to “compliance with” and change “consumption should” to “consumption protocol should”

Line 18: change “detected” to “reported”

Line 18-19: replace “reporting a general good tolerability of” with “suggesting generally good tolerance to”

Line 36: replace “to be meta-analyzed” with “for meta-analysis”

Line 37: Should p=0.004 be p=0.04? (see “Test for overall effect Z=2.04 (p=0.04) in Figure 3)

Line 44: change “although not” to “although not” to “although it was not”

DISCUSSION

Line 57: change “act at improving” to “act on to improve”

Line 60: change “leads to unability” to “precludes”

Line 61: change “analyze” to “analysis of”

Line 68: change “subject” to “the subject”

Line 73: change “while it was not for” to “but not”

Line 73: Although the ESS score was not statistically significant, it was very close, and in a direction that is consistent with a therapeutic effect (if I’m interpreting the data correctly). The authors might note that this is the case, since statistical significance at an alpha level of 0.05 is arbitrary, and, although technically not significant, the low p-value is consistent with the results of the PSQI measure.

Line 75: change “provides results hard to be summarized” to “make it difficult to generalize further about these results”

Line 77: delete “even”

Line 83: change “on” to “in”

Line 84: change “last” to “recent” and “several evidences indicated” to “several lines of evidence indicate”

Line 89: change “vague” to “vagus”

Line 92: change “is not” to “has not been”

Line 93: change “would” to “could”

Line 94: delete “real”

Line 106: change “relatively established” to “relatively well established” and add “taking the present study into account with previous analyses” at the end of the sentence ending in (105).

Line 111: delete “what”

Line 112: Provide an example or two of the potential biases – such as?

Line 115: change indicative, than PSOL, of” to “indicative than PSOL of”

Line 118: change “no improvement” to “no significant improvement”

Line 120: change “improved increasing” to “improved by increasing”

Line 135: change “due” to “useful”

Line 136: change “achieve” to “establish”

Line 144: change “participants” to “participant’s”

Line 158: change “the comprehension of” to “the analysis of” and “and/or” to “or”

Line 159: delete “eventually mitigate sleep” to “mitigating sleep”

Line 161: the statement that sleep patterns change with age needs a citation.

Line 162: delete “to perform”

Line 167: delete “that”

Line 168: change “could be” to “are likely to be”

Line 170: change “would be” to “are”

Line 172-173: change “could be established, even if” to “remains to be established, since” and “to clarify” to “definitive conclusions about”

173-174: change “Promising results suggested” to “Promising results based on subjective assessment of sleep quality”

Line 175: change “comprehension” to “understanding”

Comments on the Quality of English Language

Minor edits suggested above. 

Author Response

Thank you for your work of revision. We revised the manuscript following your comments.

Author Response File: Author Response.pdf