Correction Notice: The Effects of Circadian Rhythm on Reproductive Function (Zygote, 2025)

Concerns were raised by readers and the editorial team regarding the accuracy and validity of references in this article.

14 references were affected. These included: (i) references with non-retrievable or incorrect DOI designations, (ii) references that were mismatched with the cited content or unrelated to the statements they were intended to support, and (iii) a limited number of incorrect or incomplete bibliographic entries.

Unverifiable or inappropriate references are listed in this notice and have been replaced with validated sources, and corresponding text has been revised where necessary to ensure accurate alignment with the supporting literature. The authors and editor are satisfied the corrections do not alter the scientific conclusions of the review.

The errors arose during the manuscript preparation and reference integration process. Reference management software and automated citation tools were used to organize and insert references. These issues were not identified by the authors during the final pre-submission checks, representing an oversight in their internal review process.

The authors take full responsibility for the errors identified in the published article and sincerely apologize to the Editor-in-Chief, editorial team, and journal readers for these errors and for any confusion or concern they may have caused.

Point-by-point reference verification and corrections

Reference 1:

1. 1. Original Citation (as published): Anderson, S.T., Morgan, M.A. and Brown, A. (2023) Circadian rhythm disruption and fertility: clinical implications and mechanistic links. Reproductive Biology and Endocrinology 21(1), 15. https://doi.org/10.1186/s12958-023-00994-y

2. 2. Location in manuscript: discussion section, 1^st paragraph, final sentence

3. 3. Type of issue: Unverifiable reference

4. 4. Explanation: The cited article (Anderson et al., 2023) could not be validated by DOI, title, or database search. Therefore, the reference is considered non-retrievable.

5. 5. Correction applied: The reference was removed and the statement was retained in revised form using validated literature already present in the reference list.

6. 6. Updated references: Kennaway, D.J. (2005) The role of circadian rhythmicity in reproduction. Human Reproduction Update 11(1), 91–101.Mahoney, M.M. (2010) Shift work, jet lag, and female reproduction. International Journal of Endocrinology 2010, 813764. https://doi.org/10.1155/2010/813764

7. 7. Text modification:

   • • Original: “While murine studies have established causality, evidence from human models remains correlative and variable due to lifestyle and genetic heterogeneity (Anderson et al., 2023).”

   • • Revised: “While murine studies have established causal links between circadian disruption and impaired reproductive function, evidence from human studies remains largely associative and is influenced by lifestyle and occupational factors (Kennaway, 2005; Mahoney, 2010).”

8. 8. Impact on conclusions: No impact on overall conclusions.

Reference 2:

1. 1. Citation (as published): Brito, K.M., Tello, J., Wang, X., et al. (2023) Epigenetic consequences of circadian disruption in germline and embryo development. Nature Reviews Molecular Cell Biology 24(2), 89–101. https://doi.org/10.1038/s41580-022-00535-2

2. 2. Location in manuscript: discussion section, 2nd^st paragraph, starting with (However)

3. 3. Type of issue: Unverifiable reference

4. 4. Explanation: The cited article (Brito et al., 2023) could not be reliably validated using its title, authors, or DOI. Furthermore, no directly corresponding publication supporting the specific cited claim could be identified.

5. 5. Correction applied: The reference was removed and the sentence was revised to reflect a general knowledge gap without attributing it to a specific source.

6. 6. Updated references: None

7. 7. Text modification:

   • • Original: However, current research lacks longitudinal data tracking how such behavioral re- entrainment translates to successful pregnancy outcomes in humans. Moreover, the impact of circadian misalignment on epigenetic imprinting in gametes and early embryos is an emerging area that remains underexplored (Brito et al., 2023).

   • • Revised: “However, current research lacks longitudinal data tracking how such behavioral re-entrainment translates to successful pregnancy outcomes in humans. Moreover, the impact of circadian misalignment on epigenetic regulation in gametes and early embryos remains an emerging and incompletely understood area.”

8. 8. Impact on conclusions: No impact on overall conclusions.

Reference 3:

1. 1. Citation (as published): Challet, E., van der Spek, R. and Garaulet, M. (2022) Chrononutrition and fertility: synchronizing food intake and the circadian clock to optimize reproductive health. Nutrients 14(19), 3998. https://doi.org/10.3390/nu14193998

2. 2. Location in manuscript: Additional factors section, first paragraph

3. 3. Type of issue: Irrelevant reference / insufficient support for claim

4. 4. Explanation: Although the cited article relates to chrononutrition and circadian biology, it does not directly support the specific claims made in the manuscript regarding restoration of testosterone levels, improvement in sperm motility, and resynchronization of reproductive hormone secretion. The statement as written was therefore overly specific relative to the supporting evidence.

5. 5. Correction applied: The reference was removed and the corresponding sentence was revised to reflect a more general, evidence-consistent interpretation of lifestyle interventions without overstating specific physiological outcomes. In addition, a strong reference from the existing refences have been added.

6. 6. Updated references: Kennaway, D.J. (2005) The role of circadian rhythmicity in reproduction. Human Reproduction Update 11(1), 91–101.

7. 7. Text modification:

   • • Original: Lifestyle interventions such as circadian-aligned nutrition and physical activity have emerged as promising non-pharmacological strategies to mitigate fertility decline associated with circadian disruption. Time-aligned dietary patterns, including time- restricted feeding (TRF) and early meal timing, have been shown to restore testosterone levels, improve sperm motility and resynchronize reproductive hormone secretion disrupted by shift work or nocturnal light exposure (Challet et al., 2022).

   • • Revised: Lifestyle interventions such as circadian-aligned nutrition and physical activity have emerged as promising non-pharmacological strategies to mitigate reproductive dysfunction associated with circadian disruption. Time-aligned dietary patterns, including time-restricted feeding (TRF) and early meal timing, may help improve metabolic and hormonal regulation disrupted by circadian misalignment. Similarly, appropriately timed physical activity may support circadian alignment and overall reproductive health. These findings underscore the potential value of lifestyle-based approaches in restoring endocrine balance and reinforcing systemic circadian synchrony (Kennaway, 2005).

8. 8. Impact on conclusions: No impact on overall conclusions.

Reference 4:

1. 1. Citation (as published): Guo, J., Li, S., Zhang, T., et al. (2023) The timing of physical activity influences reproductive hormone profiles in women with disrupted circadian rhythms. Frontiers in Endocrinology 14, 1172047. https://doi.org/10.3389/fendo.2023.1172047

2. 2. Location in manuscript: Additional factors section, same paragraph (sentence discussing exercise timing)

3. 3. Type of issue: Unverifiable reference and unsupported mechanistic claim

4. 4. Explanation: The cited article could not be reliably validated, and no supporting evidence was identified for the specific mechanistic claim that timed exercise enhances Bmal1 and Per2 expression in gonadal tissues or directly improves ovulatory function as stated. The claim was therefore considered unsupported in its original form.

5. 5. Correction applied: The reference was removed and the sentence was revised to eliminate unsupported mechanistic claims while retaining a general, evidence-consistent statement regarding the role of physical activity in circadian alignment. In addition, a strong reference from the existing refences have been added.

6. 6. Updated references: Kennaway, D.J. (2005) The role of circadian rhythmicity in reproduction. Human Reproduction Update 11(1), 91–101.

7. 7. Text modification:

   • • Original: “Similarly, engaging in morning or early-day aerobic exercise enhances Bmal1 and Per2 expression in gonadal tissues and supports ovulatory function in females with irregular cycles due to circadian misalignment (Guo et al., 2023).”

   • • Revised: “Similarly, appropriately timed physical activity may support circadian alignment and overall reproductive health (Kennaway, 2005).”

8. 8. Impact on conclusions: No impact on overall conclusions.

Reference 5:

1. 1. Original Citation (as published): Chappell, P.E., White, R.S., Mellon, P.L. (2003) Circadian gene expression regulates pulsatile GnRH secretion in reproductive neuroendocrine cells. Endocrinology 144(10), 4544–4550. https://doi.org/10.1210/en.2003-0552

2. 2. Location in manuscript: Introduction, last paragraph

3. 3. Type of issue: Incorrect DOI and incorrect journal/article metadata

4. 4. Explanation: The cited study is a real publication, but the bibliographic details in the published article are incorrect. The paper by Chappell, White, and Mellon is indexed as a Journal of Neuroscience article, not an Endocrinology article, and its correct DOI is 10.1523/JNEUROSCI.23-35-11202.2003.

5. 5. Correction applied: The bibliographic details and DOI were corrected to the validated publication record. No change to the scientific statement was required.

6. 6. Updated reference: Chappell, P.E., White, R.S. and Mellon, P.L. (2003) Circadian Gene Expression Regulates Pulsatile Gonadotropin-Releasing Hormone (GnRH) Secretory Patterns in the Hypothalamic GnRH-Secreting GT1-7 Cell Line. Journal of Neuroscience 23(35), 11202–11213. https://doi.org/10.1523/JNEUROSCI.23-35-11202.2003

7. 7. Text modification: No change.

8. 8. Impact on conclusions: No impact on overall conclusions.

Reference 6:

1. 1. Original Citation (as published):Liu, Z., Li, X.M., Liu, Y., Xie, J., Wu, J. and Zhou, S. (2017) Essential roles of BMAL1 in reproductive physiology and fertility. Reproduction 154(5), 321– 331. https://doi.org/10.1530/REP-17-0102

2. 2. Location in manuscript: Introduction section, paragraph describing CLOCK –BMAL1 transcriptional feedback loop

3. 3. Type of issue: Mismatch between cited reference and supporting evidence

4. 4. Explanation: The cited article (Liu et al., 2017) does not directly support the specific experimental findings described in the manuscript regarding BMAL1 knockout models and their effects on reproductive function hence was added by mistake while listing the references. A more appropriate and directly relevant experimental study was identified.

5. 5. Correction applied: The reference was replaced with a validated experimental study that directly demonstrates the impact of BMAL1 disruption on fertility and reproductive function.

6. 6. Updated reference: Alvarez, J.D., Hansen, A., Ord, T., Bebas, P., Chappell, P.E., Giebultowicz, J.M., et al. (2008) The circadian clock protein BMAL1 is necessary for fertility and proper testosterone production in mice. Journal of Biological Rhythms 23(1), 26 36. https://doi.org/10.1177/0748730407311254

Reference 7:

1. 1. Citation (as published): Mukherjee, S., Patel, R. and Jain, R. (2022) Melatonin suppression and reproductive dysfunction following environmental exposure to endocrine disruptors: a mechanistic overview. Journal of Pineal Research 73(2), e12856. https://doi.org/10.1111/jpi.12856

2. 2. Location in manuscript: Environmental endocrine disruptors and chronodisruption section, same paragraph

3. 3. Type of issue: Unverifiable or mismatched reference

4. 4. Explanation: The cited article could not be reliably validated in its published form using its DOI, title, or authors. Furthermore, the specific mechanistic claims regarding melatonin suppression and reproductive dysfunction were not directly supported by a clearly corresponding and verifiable publication.

5. 5. Correction applied: The reference was removed and the paragraph was revised to avoid unsupported mechanistic specificity while maintaining a general, evidence-based description of endocrine disruptor effects on reproductive and circadian systems. Validated references from established literature were used to support the revised content.

6. 6. Updated references: La Merrill, M.A., Vandenberg, L.N., Smith, M.T. et al. (2020) Consensus on the key characteristics of endocrine-disrupting chemicals as a basis for hazard identification. Nature Reviews Endocrinology 16, 45–57. https://doi.org/10.1038/s41574-019-0273-8. Alvarez, J.D., Hansen, A., Ord, T., Bebas, P., Chappell, P.E., Giebultowicz, J.M., et al. (2008) The circadian clock protein BMAL1 is necessary for fertility and proper testosterone production in mice. Journal of Biological Rhythms 23(1), 26–36. https://doi.org/10.1177/0748730407311254

7. 7. Text modification:

   • • Original: “…This dual disruption of endocrine and circadian systems can lead to menstrual cycle irregularities, reduced sperm motility, altered implantation windows and increased miscarriage risk (Mukherjee et al., 2022).”

   • • Revised: “…Disruption of endocrine and circadian regulatory pathways may contribute to altered reproductive hormone signaling and impaired reproductive timing (La Merrill et al., 2020; Alvarez et al., 2008).”

8. 9. Impact on conclusions: No impact on overall conclusions.

Reference 8:

1. 1. Citation (as published): Xu, C., Hu, Y., Liu, Y., Chen, Q. and Sun, H. (2023) Disruption of circadian gene expression by endocrine-disrupting chemicals in ovarian and testicular cells. Frontiers in Endocrinology 14, 1182435. https://doi.org/10.3389/fendo.2023.1182435

2. 2. Location in manuscript: Environmental endocrine disruptors and chronodisruption section, paragraph describing effects of endocrine-disrupting chemicals on circadian genes

3. 3. Type of issue: Unverifiable reference and unsupported mechanistic claim

4. 4. Explanation: The cited article could not be reliably validated using its DOI, title, authors, or journal. In addition, no direct supporting evidence was identified for the specific mechanistic claim that endocrine-disrupting chemicals disrupt transcriptional oscillations of circadian genes (e.g. CLOCK, BMAL1, PER2) in ovarian granulosa and testicular Sertoli cells as stated.

5. 5. Correction applied: The reference was removed and the paragraph was revised to avoid unsupported mechanistic specificity while retaining a general, evidence-based relationship between endocrine disruptors and circadian regulation. In addition, validated references from the existing literature were incorporated to support the revised statement.

6. 6. Updated references: La Merrill, M.A., Vandenberg, L.N., Smith, M.T. et al. (2020) Consensus on the key characteristics of endocrine-disrupting chemicals as a basis for hazard identification. Nature Reviews Endocrinology 16, 45–57. https://doi.org/10.1038/s41574-019-0273-8. Alvarez, J.D., Hansen, A., Ord, T., Bebas, P., Chappell, P.E., Giebultowicz, J.M., et al. (2008) The circadian clock protein BMAL1 is necessary for fertility and proper testosterone production in mice. Journal of Biological Rhythms 23(1), 26–36. https://doi.org/10.1177/0748730407311254

7. 7. Text modification:

   • • Original: “…Recent evidence indicates that EDCs also disrupt the transcriptional oscillations of core circadian genes such as CLOCK, Bmal1 and Per2 in ovarian granulosa cells and testicular Sertoli cells, resulting in asynchrony of gonadal hormone secretion and gametogenic timing (Xu et al., 2023).”

   • • Revised:

     “…Emerging evidence suggests that

     EDC exposure may also interfere with circadian regulatory pathways, including the expression and function of core clock genes such as CLOCK, BMAL1 and PER2. Given that circadian clock components are expressed in reproductive tissues and contribute to the temporal regulation of steroidogenesis and gametogenesis, disruption of these pathways may lead to asynchrony in hormone secretion and reproductive timing (La Merrill et al., 2020; Alvarez et al., 2008).”

   • 8. Impact on conclusions: No impact on overall conclusions.

Reference 9:

1. 1. Citation (as published): Nakamura, T.J., Sellix, M.T. and Menaker, M. (2022) The circadian system and fertility: a clinical update on chronotherapy. Fertility and Sterility 118(5), 803–811. https://doi.org/10.1016/j.fertnstert.2022.07.003

2. 2. Location in manuscript: Discussion section, paragraph discussing therapeutic and lifestyle interventions

3. 3. Type of issue: Unverifiable reference and unsupported specific claim

4. 4. Explanation: The cited article could not be reliably validated, and the specific claims regarding time-restricted feeding, light therapy, and exercise-based interventions restoring reproductive rhythms were not directly supported by a verifiable corresponding publication.

5. 5. Correction applied: The reference was removed and the sentence was revised to reflect a more general, evidence-consistent interpretation of circadian-aligned interventions without overstating specific therapeutic effects.

6. 6. Updated references: Kennaway, D.J. (2005) Mahoney, M.M. (2010)

7. 7. Text modification:

   • • Original: “…TRF, light therapy and exercise… can partially restore reproductive rhythms… (Nakamura et al., 2022).”

   • • Revised: “…personalized interventions aligned with circadian timing, including dietary and behavioral strategies, may help improve circadian and reproductive function in individuals exposed to shift work or nocturnal light (Kennaway, 2005; Mahoney, 2010).”

8. 8. Impact on conclusions: No impact on overall conclusions.

Reference 10:

1. 1. Citation (as published): Schiavi, M.C., Faiano, P., D’Oria, O., et al. (2022) Circadian rhythm and female genital tract: interactions with microbiota and implications for fertility. Reproductive Sciences 29(4), 1102–1111. https://doi.org/10.1007/s43032-021-00638-0

2. 2. Location in manuscript: Vaginal health subsection

3. 3. Type of issue: Unverifiable or insufficiently supported reference

4. 4. Explanation: The cited article could not be reliably validated in its published form using its DOI, title, or authors. In addition, the specific claims regarding circadian regulation of vaginal microbiota composition and infection resistance were not directly supported by a verifiable corresponding publication, and the statement as written was overly specific relative to available evidence.

5. 5. Correction applied: The reference was removed and the paragraph was revised to retain a focus on vaginal physiology while avoiding unsupported mechanistic claims. The revised version presents a general, evidence-consistent description of circadian regulation in reproductive tissues.

6. 6. Updated references: Kennaway, D.J. (2005) The role of circadian rhythmicity in reproduction. Human Reproduction Update 11(1), 91–101. Alvarez, J.D., Hansen, A., Ord, T., Bebas, P., Chappell, P.E., Giebultowicz, J.M., et al. (2008) The circadian clock protein BMAL1 is necessary for fertility and proper testosterone production in mice. Journal of Biological Rhythms 23(1), 26–36. https://doi.org/10.1177/0748730407311254

7. 7. Text modification:

   • • Original: “The circadian clock also exerts regulatory control over the vaginal epithelium, which undergoes cyclical changes influenced by estrogen levels and local immune responses. Core clock genes such as BMAL1 and CLOCK have been shown to modulate epithelial barrier function and mucosal immunity in reproductive tissues, including the vagina. Disruptions in circadian rhythms – such as those caused by shift work or irregular sleep – can alter vaginal microbiota composition and reduce resistance to infections, thereby compromising vaginal health and fertility (Schiavi et al., 2022).”

   • • Revised: “The circadian clock also contributes to the regulation of vaginal physiology, including epithelial turnover, hormonal responsiveness, and local immune function. These processes are influenced by cyclic hormonal changes, particularly estrogen, and are essential for maintaining vaginal tissue homeostasis. Emerging evidence suggests that circadian rhythms may play a role in coordinating these functions within reproductive tissues. Disruptions in circadian timing, such as those associated with shift work or irregular sleep patterns, may alter local tissue function and immune responses, potentially impacting vaginal health and overall reproductive function (Kennaway, 2005; Alvarez et al., 2008).”

8. 8. Impact on conclusions: No impact on overall conclusions.

Reference 11:

1. 1. Citation (as published): Stanton, M.E., Chang, L., Barakat, R., et al. (2023) Circadian gene expression regulates preimplantation development and blastocyst quality. Reproduction 165(2), R101–R113. https://doi.org/10.1530/REP-23-0104

2. 9. Location in manuscript: Circadian control of early embryogenesis and implantation section

3. 10. Type of issue: Unverifiable reference and unsupported mechanistic claim

4. 11. Explanation: The cited article could not be reliably validated using its DOI, title, or authors. In addition, the manuscript contained highly specific mechanistic claims regarding preimplantation development, pluripotency gene regulation (OCT4, SOX2), and blastocyst formation that were not directly supported by verifiable literature sources.

5. 12. Correction applied: The reference was removed and the paragraph was revised to eliminate unsupported mechanistic detail while retaining a general, evidence-consistent description of circadian regulation in early embryonic development.

6. 13. Updated references: Alvarez, J.D., Hansen, A., Ord, T., Bebas, P., Chappell, P.E., Giebultowicz, J.M., et al. (2008) The circadian clock protein BMAL1 is necessary for fertility and proper testosterone production in mice. Journal of Biological Rhythms 23(1), 26–36. https://doi.org/10.1177/0748730407311254 Kennaway, D.J. (2005) The role of circadian rhythmicity in reproduction. Human Reproduction Update 11(1), 91–101.

7. 14. Text modification:

   • • Original: “…resulting in delayed cleavage, downregulation of pluripotency genes such as OCT4 and SOX2, impaired blastocyst expansion and ultimately reduced implantation success (Stanton et al., 2023).”

   • • Revised: “…has been associated with impaired reproductive outcomes and reduced fertility in animal models. These findings suggest that circadian regulation may play an important role in early embryogenesis and implantation, although the precise mechanisms remain incompletely understood (Alvarez et al., 2008; Kennaway, 2005).”

8. 15. Impact on conclusions: No impact on overall conclusions.

Reference 12:

1. 1. Citation (as published): Vetter, C., Devore, E.E., Wegrzyn, L.R., Massa, J., Speizer, F.E., Kawachi, I. and Schernhammer, E.S. (2018) Association between rotating night shift work and risk of coronary heart disease among women. JAMA 320(23), 2448–2458. https://doi.org/10.1001/jama.2018.14276

2. 2. Location in manuscript: Longitudinal studies section

3. 3. Type of issue: Irrelevant reference mistakenly added

4. 4. Explanation: The cited article is a valid epidemiological study examining cardiovascular outcomes associated with shift work; however, it does not directly relate to reproductive outcomes or longitudinal assessment of circadian disruption in reproductive health. Therefore, it does not appropriately support the statement in which it was cited and it wasn’t necessary to be added since the section is discussing about future research papers, hence this wrong reference was added misk=takenly while listing references.

5. 5. Correction applied: The reference was no needed and was removed

6. 6. Updated references: None

7. 7. Text modification: None, only irreverent citation was removed

8. 8. Impact on conclusions: No impact on overall conclusions.

Reference 13:

1. 1. Citation (as published): Waters, A. and Devaney, T. (2013) The role of exercise in maintaining health and preventing disease: an analysis of circadian rhythms and hormonal balance. Journal of Endocrinology 219(1), R25–R36.

2. 2. Location in manuscript: Testicular function section, final paragraph

3. 3. Type of issue: Unverifiable reference

4. 4. Explanation: The cited article could not be reliably validated using its title, authors, or journal. In addition, the statement in which it was cited concerns the general influence of lifestyle factors on circadian and reproductive health, which requires support from a validated and directly relevant source.

5. 5. Correction applied: The reference was removed and replaced with a validated review article that supports the relationship between lifestyle factors, circadian regulation, and reproductive function.

6. 6. Updated references: Ono, M., et al. (2025) Influence of lifestyle and the circadian clock on reproduction. Reproductive Medicine and Biology.

7. 7. Text modification: None, since the claim is matching the new reference being added.

8. 8. Impact on conclusions: No impact on overall conclusions.

Reference 14:

1. 1. Citation (as published): Xie, Y., Ma, C., Zhou, J., et al. (2022) Clock gene expression and oocyte quality: circadian control of zygote competence.Cell and Tissue Research 388(3), 491–502. https://doi.org/10.1007/s00441-021-03568-z

2. 2. Location in manuscript: circadian regulation of spermatogenesis, last paragraph.

3. 3. Type of issue: Unverifiable reference and unsupported mechanistic claim

4. 4. Explanation: The cited article could not be reliably validated using its DOI, title, or authors. In addition, the manuscript included highly specific mechanistic claims regarding granulosa and theca cell function, LH surge regulation, and follicular viability that were not directly supported by verifiable literature.

5. 5. Correction applied: The reference was removed and replaced with a validated review article supporting the broader relationship between circadian disruption and reproductive endocrine function. The sentence was revised to eliminate unsupported mechanistic detail.

6. 6. Updated references: Gamble, K.L., Resuehr, D. and Johnson, C.H. (2013) Shift work and circadian dysregulation of reproduction. Frontiers in Endocrinology 4, 92. https://doi.org/10.3389/fendo.2013.00092

7. 7. Text modification:

   • • Original: “…granulosa and theca cells exhibit oscillatory expression… delay LH surge… reduce follicle viability (Xie et al., 2022).”

   • • Revised: “Similarly, in the ovary, circadian clock genes are expressed in reproductive tissues and contribute to the regulation of hormonal signaling and ovarian function. Disruption of circadian rhythms—whether due to genetic alterations or environmental factors such as light at night—has been associated with altered gonadotropin secretion, impaired steroidogenesis and reduced reproductive efficiency (Gamble et al., 2013).”

8. 8. Impact on conclusions: No impact on overall conclusions.

Reference 15:

1. 1. Citation (as published): Yang, H., Lee, K., Jeong, J.Y., et al. (2021) Disruption of CLOCK-Bmal1 impairs spermiogenesis and sperm DNA integrity in mice. Biology of Reproduction 105(2), 458–468. https://doi.org/10.1093/biolre/ioaa212

2. 2. Location in manuscript: Circadian regulation of spermatogenesis section

3. 3. Type of issue: Unverifiable reference and unsupported detailed mechanistic claim

4. 4. Explanation: The cited article could not be reliably validated using its DOI, title, or authors. In addition, the manuscript included highly specific mechanistic claims regarding chromatin condensation, protamine expression (PRM1/2), acrosome morphology, and DNA fragmentation that were not directly supported by verifiable literature sources.

5. 5. Correction applied: The reference was removed and the paragraph was revised to eliminate unsupported molecular detail while retaining a general, evidence-consistent description of circadian regulation of spermatogenesis.

6. 6. Updated references: Alvarez, J.D., Hansen, A., Ord, T., Bebas, P., Chappell, P.E., Giebultowicz, J.M., et al. (2008) The circadian clock protein BMAL1 is necessary for fertility and proper testosterone production in mice. Journal of Biological Rhythms 23(1), 26–36. https://doi.org/10.1177/0748730407311254. Boden, M.J. and Kennaway, D.J. (2006) Circadian rhythms and reproduction. Reproduction 132(3), 379–392.

7. 7. Text modification:

   • • Original: “…characterized by impaired chromatin condensation due to downregulation of protamine 1 and 2 (PRM1/2), malformed acrosomes, reduced motility and increased DNA fragmentation…”

   • • Revised: “…has been associated with impaired spermatogenesis and reduced fertility in animal models (Alvarez et al., 2008; Boden & Kennaway, 2006).”

8. 8. Impact on conclusions: No impact on overall conclusions.