Lu and colleagues present a meta-analysis on the effect of phototherapy on cognitive function and behavioral changes in patients with dementia. The effect on cognitive function was extracted from three publications and showed a significant impact on cognition as measured by the MMSE. No significant changes were observed on behavioral and sleep measures.

Introduction;
- The last sentence in the second paragraph refers to phototherapy as a "typical non-pharmacological therapy". It is unclear what the authors mean by "typical".

Material and Methods:
- 2.1 section, third paragraph, second sentence; "five main regions" does not seem correct. Could it be groups or domains instead?
- 2.2 section mentions Table A1, however I infer this should be supplementary table 1

Results:
- 3.1 the flow diagram values do not match the text. The diagram mentions 65 articles were excluded and the text 58. The diagram mentions 15 articles were included in the analysis, and the text 16.
- 3.2 should include the exact percentage of female participant in either the treatment or control arms
- 3.2 avoid referring to patients with dementia as demented patients
- Table 1 is difficult to read with the vertical data. I would recommend optimizing data display and space, and ideally have information displayed horizontally
- 3.5.1 Why were only three studies included? What cognitive measures (other than the MMSE) were used in the remaining studies? The large variation in raw MMSE value between studies should be added as a limitation.
- 3.5.2 Changes in CMAI seem to derive from only one study

Discussion:
- Second paragraph, I would avoid saying "our finding" since this is a meta-analysis
- Please replace "not totally demented" with a better descriptive term such a mild to moderate dementia
- I would recommend including the frequency and most common adverse events with phototherapy
- Specify which outcome measures were not analyzed
- Please emphasize that the changes in cognition were extracted from only three articles, why was this the case? Could different types of dementia be compared?
- In dementia, most interventions are aimed to slowing the decline of cognitive function. Is it realistic to see improvement in the MMSE scores vs a slowing in the decline?