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Correspondence |

Demand for Multicentric Climatic Research to Investigate the Relationship Between Sleep Apnea and Other Disorders and SeasonalitySeasonality and Sleep Apnea FREE TO VIEW

Felipe Ramos-Xavier; Laura Bennedsen; Helena Hachul, MD, PhD; Monica L. Andersen, PhD; Sergio Tufik, MD, PhD
Author and Funding Information

From the Faculdade de Medicina de Marília (FAMEMA) (Mr Ramos-Xavier); Department of Bioengineering (Ms Bennedsen), University of Maryland; Departamento de Psicobiologia e Ginecologia (Dr Hachul) and Departamento de Psicobiologia (Drs Andersen and Tufik), Universidade Federal de São Paulo; and Departamento de Ginecologia (Dr Hachul), Casa de Saúde Santa Marcelina.

Correspondence to: Monica L. Andersen, PhD, Departamento de Psicobiologia, Universidade Federal de São Paulo, Rua Sena Madureira, Rua Napoleão de Barros, 925, São Paulo, 04024002, Brazil; e-mail: ml.andersen12@gmail.com


Financial/nonfinancial disclosures: The authors have reported to CHEST that no potential conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article.

Reproduction of this article is prohibited without written permission from the American College of Chest Physicians. See online for more details.


Chest. 2012;142(6):1689. doi:10.1378/chest.12-1543
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Published online
To the Editor:

The merit of the work by Cassol and colleagues1 (see page 1499) is outstanding. The study performed a retrospective clinical analysis of an impressive 7,523 individuals suspected of having some type of sleep disorder over the span of 10 years. The authors aimed to examine whether a relationship between seasonality and the severity of obstructive sleep apnea (OSA) exists. Through elaborate statistical analysis, results showed an increase in the incidence of more-severe OSA in the winter compared with that in the summer. However, the authors acknowledge that the retrospective nature of the study limits the ability of the main question to be adequately addressed.

This study has great potential impact, and the authors deserve congratulations for the complexity of the research. However, it should be noted that it was performed in only one location (Porto Alegre, Brazil), and the results do not accurately represent a global climatic characteristic. An important point that defines a subtropical climate, as that of the study’s location, is the presence of four clearly defined seasons that vary greatly in temperature range. Such a wide variation of temperatures does not occur at all latitudes. As a result, a well-defined winter has a greater impact on the health of the population, causing more individuals to seek medical assistance and consequently leading to a larger number of breathing disorders. OSA has a high prevalence, reaching about 33% of a metropolitan city2 and demonstrating the relevance of studying relationships branching from this common disease in the contemporary world.

Another prominent factor was the high prevalence of smokers found in this sample. Conway et al3 also reported a similar prevalence of collectively about 37%, suggesting a strong association between sleep fragmentation and oxyhemoglobin desaturation during sleep. Thus, smoking habits, a predictive factor for breathing disorders, can be linked to an increase in the apnea-hypopnea index used to indicate sleep apnea.

The question posed in this study of whether OSA is a winter disease also raises another important question: the existence of seasonality in other types of sleep disorders. To investigate this possibility, future research is needed to elucidate this association, using the current study as a preliminary base. Seasonality in relation to sleep disorders is an innovative topic and should be investigated as a multicentric framework in regions with distinct climates to evaluate the changes in several sleep disturbances, including insomnia, movement disturbances, and sleep apnea, relative to seasonal variations.

References

Cassol CM, Martinez D, Silva FABS, Fischer MK, Lenz MD, Bós AJG. Is sleep apnea a winter disease? Meteorologic and sleep laboratory evidence collected over 1 decade. Chest. 2012;142(6):1499-1507.
 
Tufik S, Santos-Silva R, Taddei JA, Bittencourt LR. Obstructive sleep apnea syndrome in the Sao Paulo Epidemiologic Sleep Study. Sleep Med. 2010;11(5):441-446. [CrossRef] [PubMed]
 
Conway SG, Roizenblatt SS, Palombini L, et al. Effect of smoking habits on sleep. Braz J Med Biol Res. 2008;41(8):722-727. [CrossRef] [PubMed]
 

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References

Cassol CM, Martinez D, Silva FABS, Fischer MK, Lenz MD, Bós AJG. Is sleep apnea a winter disease? Meteorologic and sleep laboratory evidence collected over 1 decade. Chest. 2012;142(6):1499-1507.
 
Tufik S, Santos-Silva R, Taddei JA, Bittencourt LR. Obstructive sleep apnea syndrome in the Sao Paulo Epidemiologic Sleep Study. Sleep Med. 2010;11(5):441-446. [CrossRef] [PubMed]
 
Conway SG, Roizenblatt SS, Palombini L, et al. Effect of smoking habits on sleep. Braz J Med Biol Res. 2008;41(8):722-727. [CrossRef] [PubMed]
 
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