Comments on abstract, title, references

● Is the aim clear? YES ● Is it clear what the study found and how they did it? YES ● Is the title informative and relevant? YES ● Are the references: ● Relevant?YES ● Recent?YES ● Referenced correctly?YES ● Are appropriate key studies included?YES

Comments on introduction/background

● Is it clear what is already known about this topic? Not really. The authors should provide more details about the effects of light color on alertness, especially the findings from other research groups, rather than simply put “In previous studies [5, 6], we have demonstrated that exposure to melanopsinstimulating (melanopic) component-rich blue light enhances autonomic arousal and behavioral alertness.”

● Is the research question clearly outlined? Not really. The authors should write more about the motivation to do this study.

● Is the research question justified given what is already known about the topic? No. First, the authors didnot provide enough information about the state-of-art of this topic. Second, the authors did not give their reasons to do this study

Comments on methodology

● Is the process of subject selection clear? No. The authors should provide the recruit requirements of participants （e.g., chronotype） and the determination of sample size. Eight participants seem too little.

● Are the variables defined and measured appropriately? Yes.

● Are the study methods valid and reliable? The dependant variables and independent variables are valid and reliable. However, the sample size was too small.

● Is there enough detail in order to replicate the study? Mostly yes. However, the report of light parameters should include more details, such as the spectrum of light to help the readers know more about the light setting.

Comments on data and results

● Is the data presented in an appropriate way? Mostly yes. However, it seems that there is a outlier in Table 2 for heart rate in orange light condition. It would be better if the authors provide some details about the method they used to rule out the outliers.

● Tables and figures relevant and clearly presented? Yes.

● Appropriate units, rounding, and number of decimals? Yes.

● Titles, columns, and rows labelled correctly and clearly? Yes.

● Categories grouped appropriately? Yes.

● Does the text in the results add to the data or is it repetitive? The text in the results add to the data.

● Are you clear about what is a statistically significant result? Yes.

● Are you clear about what is a practically meaningful result? Yes.

Comments on discussion and conclusions

● Are the results discussed from multiple angles and placed into context without being overinterpreted? As mentioned before, the review of related literature is not throughly.So the discussion about the results with previous findings is only limited to several studies. And the angles employed in the discussion seems really limited.

● Do the conclusions answer the aims of the study? Yes.

● Are the conclusions supported by references or results? Yes.

● Are the limitations of the study fatal or are they opportunities to inform future research? The limitations are not fatal and inform future research.

● Was the study design appropriate to answer the aim? Yes.

● What did this study add to what was already known on this topic? Exposure to blue light during lunch break, compared with that to orange light, enhances autonomic arousal during exposure, but has no sustained effect on autonomic arousal or behavioral alertness after exposure.

● What were the major flaws of this article? Little sample size.

● Is the article consistent within itself? Yes.

Overall statement or summary of the article and its findings in your own words： This study compared the effects of blue light and orange light on autonomic arousal （heart rate variability）and behavioral alertness （psychomotor vigilance tests）in office workers and found exposure to blue light during lunch break, compared with that to orange light, enhances autonomic arousal during exposure, while has no sustained effect on autonomic arousal or behavioral alertness after exposure.

Overall strengths of the article and what impact it might have in your field： The results of this paper clear presented. It might inform that blue light is effective in affecting autonomic arousal while has limited effects on behavioral alertness.

Specific comments on weaknesses of the article and what could be done to improve it:

Major points in the article which needs clarification, refinement, reanalysis, rewrites and/or additional information and suggestions for what could be done to improve the article.

1. identity the novelty of this study
2. clarify the motivation of this study
3. review the related studies throughly

Minor points like figures/tables not being mentioned in the text, a missing reference, typos, and other inconsistencies.

1. state the determination of sample size
2. add the figure for the spectrum of these two light conditions