1. Introduction
Extensive studies have been conducted in the world to identify the factors associated with cardiovascular disease. Some studies have suggested the role of sleep disorders, including daytime drowsiness, in cardiovascular disease [1, 2]. Overall, studies have confirmed the association between drowsiness and cardiovascular indicators, but there is disagreement about which of these indicators is associated with daily drowsiness and how it is related. Studies on the relationship between daily drowsiness and cardiovascular indices have been performed mainly on a limited group of patients and the study on the general elderly population has been small. Considering that daily drowsiness is one of the most common disorders in the elderly, in this study we aimed to investigate the relationship between daily drowsiness and cardiovascular health indicators in a group of the general Iranian elderly population.
2. Materials and Methods
321 elderly people covered by health centers of Kiar city in Chaharmahal and Bakhtiari province participated in this cross-sectional study using available sampling from all centers. Inclusion criteria include age 60 years and older, willingness to participate in research, no severe cognitive and psychological disorders, ability to communicate verbally; Exclusion criteria included the use of any psychedelic or hypnotic drug, incomplete completion of the questionnaire, refusal to perform or perform incomplete tests, acute illness and any other diseases affecting mental function and alertness and test results. Data were collected using demographic characteristics questionnaire, Epworth Excessive Sleepiness Scale (ESS), Measurement of anthropometric indices, and paraclinical tests. Among anthropometric indices, body mass index BM (BMI) in three normal groups (24.9-18.5), overweight (25-29.9), obesity (30 and more), waist circumference (As an indicator of abdominal obesity equal to or greater than 88 cm in women and equal to or greater than 102 cm in men), neck circumference (as an indicator of cervical obesity equal to 37 cm and above in men and 34 cm and above in women) and blood pressure (systolic blood pressure 140 mmHg and above and diastolic blood pressure 90 mmHg and above as high blood pressure) were measured. Paraclinical data include measurement of fasting blood sugar (110 mg and above as high blood sugar), triglyceride (150 mg / dL and above as high triglyceride), and cholesterol (200 mg / dL and above as high cholesterol) were also collected. The cut-off point for distinguishing drowsiness of clinical significance was considered in the Opworth questionnaire 10 [3, 4]. To analyze the data, SPSS v. 23 statistical software, descriptive statistics, and Chi-square, Mann-Whitney, Kruskal-Wallis, and Spearman correlation coefficients were used. This study has an ethics code, IR.USWR.REC.1398.102 from the Medical Ethics Committee of the University of Rehabilitation Sciences and Social Health.
3. Results
The mean age of the sampled elderly was 68.7 years with a standard deviation of 7.28 and 69.2% of them were women and 76.6% of them were married. Also, most of the participants were unemployed or housewives (76%) and 77.3% were illiterate. The history of cardiovascular disease and physical disease were 20.9% and 32.1%, respectively. More than 55% had a history of hypertension and 7.8% had a history of smoking. The participant's body mass index in the normal range, overweight, and obesity were 31.8%, 39.9%, and 28.3%, respectively. In 69.2% of the study population, waist circumference was in the abnormal range; Also, 62% had abnormal neck circumference; Systolic and diastolic hypertension were also reported to be 19.3% and 16.2%, respectively. 21.8% of the blood sugar sample was abnormal and 76.3% and 38.9% had abnormal cholesterol and triglyceride levels, respectively.
The results showed that 23.67, 19 and 7% of the elderly had mild to severe drowsiness, respectively, and there was a significant relationship between daily drowsiness and age (p=0.03, r=0.121). Age over 70 years was significantly associated with high ESS scores (P=0.003) and also between daily drowsiness and body mass index (r=0.172, p=0.002), systolic blood pressure (r=0.235, p<0.001) and diastolic blood pressure (r=0.216, p<0.001), abdominal obesity (r=0.293, p<0.001) and neck circumference (r=0.239, p<0.001), a significant positive correlation was observed. The relationship between daily drowsiness and the number of drugs used was also significant and positive (p<0.001, r=0.226). But other variables such as triglyceride (p=0.374), cholesterol (p=0.824), and fasting blood sugar (p=0.084) were not significantly associated with daily drowsiness. Comparison of the mean score of drowsiness between men and women did not show a significant difference (P=0.158). In addition, a comparison of the two groups with and without drowsiness (based on cut-off point 10) showed that there was a significant difference between drowsiness with body mass index (p=0.003), history of hypertension (p≤0.001), high systolic blood pressure (0.015), diastolic blood pressure (p=0.002), fasting blood sugar (p≤0.001), and neck circumference (p=0.002) between the two groups.
4. Discusion and Conclusion
This study confirmed the relationship between daily drowsiness and some indicators of cardiovascular health including body mass index, hypertension, abdominal obesity, and neck circumference. It also showed that fasting blood sugar levels were significantly different between the two groups with and without daily drowsiness. The high prevalence of daily drowsiness in the elderly and the results of other research on the relationship between daily drowsiness and cardiovascular disease warns the need for further study on daily drowsiness in the elderly, how to measure and study its causes, and design and implementation of preventive interventions. It is recommended that daily drowsiness assessments be performed in routine care programs for the elderly, especially the elderly with cardiovascular disease, to detect both disorders early and reduce the rate of both disorders. It is also suggested that the cardiovascular condition in patients with daily drowsiness and vice versa be considered.

Ethical Considerations
Compliance with ethical guidelines
This study was approved by the Ethics Committee of the University of Social Welfare and Rehabilitation Sciences (Code: IR.USWR.REC.1398.102). All ethical principles are considered in this article. The participants were informed about the purpose of the research and its implementation stages. They were also assured about the confidentiality of their information. They were free to leave the study whenever they wished, and if desired, the research results would be available to them.

Funding
This research did not receive any grant from funding agencies in the public, commercial, or non-profit sectors. 

Authors' contributions
All authors equally contributed to preparing this article.

Conflicts of interest
The authors declared no conflict of interest.


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