Purpose: The present study analyzed the production on metabolic syndrome and sleep disorders in Brazil in the indexed scientific literature.

Methods: Keywords such as “ Metabolic Syndrome”, “Cardiometabolic Risk Factors”, and “Sleep Wake Disorders” were used to find relevant research papers in PubMed and Latin American and Caribbean Literature in Health Sciences – Virtual Health Library (LILACS - VHL). Additionally, a table was built with the synthesis of the publications recovered in the two databases to characterize the publications found and an analysis of textual bodies and similarity was carried out, in order to better understand the connections between the terms that emerged from the analyzed abstracts.

Results: Regarding the central theme, of the 15 publications 9 were related to the quantity and quality of sleep, focusing mostly on obstructive sleep apnea (OSA), with metabolic syndrome. In addition to these, 2 publications present the relationship between metabolic syndrome with ethnicity and chronic non-communicable diseases. And 4 publications have as their main theme sleep-related disorders only. The similarity analysis showed us that there is a relationship between the structure that circumscribes the term “sleep” with strong connective features, that is, with greater width, between the aforementioned term and the following: “metabolic syndrome”; "index"; “risk factor”, “obstructive sleep apnea – OSA” and “association”.

Conclusion: This short review evidenced that the theme related to metabolic syndrome and sleep disorders in Brazil, based on the search strategies carried out, showed little literature, as well as indicating a high relationship perceived by the mathematical model of co-occurrences between the term “sleep” with “OSA”, “risk factor” and “metabolic syndrome”.

Keywords: metabolic syndrome, cardiometabolic risk factors, sleep wake disorders

Automatism, perfectionism and immediacy are terms that characterize the process of urbanization and industrialization that have taken place over the last few centuries. There is a growing demand for productivity, in addition to the depletion of errors, generating an extremely stressful pattern and harmful to the health of those involved. This can generate physical and organic diseases, which currently have manifested as difficulties sleeping, weight gain and increased blood pressure. Associated with this process, the change in the food pattern led to a greater consumption of industrialized products, which contain a lot of sodium, sugar and preservatives, dispensing with the consumption of vegetable and vegetable fiber. Thus, the diet became more hypercaloric and fatty, and less organic and healthy, which, associated with considerable deleterious changes in the human standard of living – with a greater load of daily stress – considerably affected the pattern of diseases expressed in the population.

According to the 2018 Institute for Health Metrics and Evaluation (IHME), cardiovascular diseases, such as ischemic heart disease and cerebrovascular disease, rank first and second as the leading cause of death.¹ This ends up being a portrait of all the change brought about by industrial and technological revolutions, which can bring standards of living that are increasingly harmful to people's health. If carelessness is continued, there will be an increase in risk factors for metabolic syndrome and problems secondary to stress, such as difficulty sleeping.

Metabolic Syndrome (MS) is a term that describes a set of risk factors for chronic diseases, being established through interactions of genetic and environmental characteristics, with a plurimetabolic character. It is defined, according to the International Diabetes Federation (IDF), by the presence of two or more risk factors for cardiovascular diseases, namely: systemic arterial hypertension (≥130/85 mmHg or in drug treatment); elevated fasting glucose (≥100 mg/dL or diagnosis of type 2 diabetes); triglycerides equal to or greater than 150 mg/dL (or in specific treatment for this lipid abnormality); HDL cholesterol less than 40 mg/dL in men and less than 50 mg/dL in women (or undergoing specific treatment for this lipid abnormality); central obesity (waist circumference equal to or greater than 94 cm for men and equal to or greater than 80 cm for women).²

 In turn, sleep is defined as a readily reversible suspension of the sensorimotor interaction with the environment, being a complex behavioral state of physiological reduction of the level of consciousness, maintaining patterns of brain activity. On the other hand, wakefulness is a state in which there is a high potential for sensitivity and efficient receptivity to external stimuli, keeping the person in an alert state. For its interaction, the sleep-wake cycle works through a neurochemical mechanism of activation and inhibition in the brainstem and cerebral cortex, but a deregulation can lead to Sleep Disorders. Thus, these are described as sleep-wake disorders, in which the sleep-wake schedule or pattern is associated with the circadian rhythm, which affects the duration, timing, and/or rigidity of the sleep-wake cycle relative to the day/night cycle.^3,4

Based on the above scenario, the objective of this present study is to analyze the production on metabolic syndrome and sleep disorders in Brazil in the indexed scientific literature.

The selection of databases is an essential part of the search for evidence and was based on the recommendations of the reference manuals of synthesis studies. They recommend searching international databases, even when the objective is to review geographically, temporally or language-based, with the premise that scientific literature presupposes a reach beyond these parameters. Thus, our review, which has a predetermined geographic scope (Brazil), meets the criteria for inclusion of mandatory international and regional bases. Following the guidance of the JBI Manual for Evidence Synthesis,⁵ this search consisted of three steps: selection of information sources; conceptual mapping of the research subject; and construction of the search strategy. In the first one, we identified the relevant databases for this review, including the Medical Literature Analysis and Retrieval System Online - consultation via PubMed (MEDLINE/PubMed) a reference base for the world's biomedical literature (mandatory in the recommendations of systematic literature reviews in health area). The second base selected was the regional base Latin American and Caribbean Literature in Health Sciences – Virtual Health Library (LILACS - VHL), as they cover the technical-scientific literature of the Latin American and Caribbean region, including Brazil.

We performed the conceptual semantic mapping of the terms of interest, in natural and documentary language, in the controlled vocabularies of Descriptors in Health Sciences (DeCS) and Medical Subject Headings (Mesh). The identification of the most relevant and representative terms of the subject in question gave rise to the analysis of sensitivity and specificity, considering the relevance, pertinence and relevance of the terms in the selected databases according to the recommendation of the JBI Manual for Evidence Synthesis.

The sensitivity analysis of the terms identified in each database aimed to: assess their accuracy; check spelling variations, synonyms and permutation of compound terms; avoid “explosion” to non-relevant topics; identify the interpretation of terms by the different bases; balance the search strategy between sensitivity, broader, and specificity, more restricted, where the proportion between the number of documents retrieved and their relevance to the search are considered. For the composition of the strategy, we used the logical operators OR and AND in the relationship between the terms listed in order to verify the precision and recall of records, the ability to retrieve the largest possible number of records on the researched topic, as well as the specificity of the items recovered.⁶

Following is the description of the final search strategy in the two bases listed for the study: 1- PubMed ((Metabolic Syndrome[MeSH Terms]) OR (Metabolic Syndrome[Title/Abstract]) OR (Cardiometabolic Risk Factors[MeSH Terms]) OR (Cardiometabolic Risk Factors[Title/Abstract])) AND (Sleep Wake Disorders[MeSH Terms]) OR (Sleep Wake Disorders[Title/Abstract) AND (Brazil[Title/Abstract] OR Brasil[Title/Abstract]); 2- LILACS – BVS  (tw:"Síndrome Metabólica" OR "Metabolic Syndrome" OR "Cardiometabolic Risk Factors" OR "Fatores de Risco Cardiometabólico" ) AND (tw:"Transtornos do Sono-Vigília" OR "Sleep Wake Disorders" OR "Distúrbios do Sono" OR "Sleep Disorders" OR "Sleep Disorder") AND (tw:"Brasil" OR "Brazil").

In addition, a characterization of the indexed scientific production was performed, as well as a compilation of the respective abstracts with the analysis of textual corpus and similarity, built via Iramuteq Software.⁷

The search strategies in the scientific literature applied in PubMed and LILACS – VHL retrieved, respectively, 11 and 6 publications, with 1 of them duplicated in both bases. Thus, the search resulted in a total of 15 publications to be analyzed.

In Figure 1, there is a description of them in terms of: publication title; authors' names; journal title; country of the journal; original language of publication; year of publication; and central theme. In sequence, Figure 2 is presented, which refers to the similarity graph of the abstracts in English of the publications.

It is important to point out that, due to the small number of papers recovered by the search strategies, it was decided not to carry out the screenings by title, abstract and full text, a method usually performed in synthesis studies, which culminated in the analysis of all of them.

Analyzing the publications described in Figure 1, which cover the period from 2011 to 2021, the countries of origin of the journals are: Brazil (6 publications), United States (4 publications), England (2 publications), Netherlands (2 publications) and Denmark (1 publication), with the vast majority presenting English as the original language. Regarding the central theme, 9 of them are related to the quantity and quality of sleep, focusing mostly on obstructive sleep apnea (OSA), with metabolic syndrome.^8-16 In addition to these, 2 publications present the relationship between metabolic syndrome with ethnicity¹⁷ and chronic non-communicable diseases.¹⁸ And 4 publications have as their main theme sleep-related disorders only.^19-24

In Figure 2, it is possible to verify, through the analysis of similitude, that there is a relationship between the structure that circumscribes the term “sleep” with strong connective features, that is, with greater width, between the aforementioned term and the following: “metabolic syndrome”; "index"; “risk factor”, “obstructive sleep apnea – OSA” and “association”. It is worth mentioning that similitude is a mathematical method that brings a simplification of reality and shows the correlations evidenced by the mathematical model.

Figure 2 Similarity graph of abstracts in english of recovered publications.

This short review evidenced that the theme related to metabolic syndrome and sleep disorders in Brazil, based on the search strategies carried out, showed little literature, as well as indicating a high relationship perceived by the mathematical model of co-occurrences between the term “sleep” with “OSA”, “risk factor” and “metabolic syndrome”.

Our findings suggest the need for further studies that seek to better understand the relationship between metabolic syndrome and sleep disorders, expanding the view on what has already been produced on the subject in the world scientific literature.

None.

None.

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