The Relationship between Nutritional Status, Sleep Duration, Stress Level with Blood Pressure of Nurse Night Shift in the Hospital: Cohort Study

: Objective: Hypertension as a cardiovascular disease occurs due to an uncontrolled increase in blood pressure. Night shift nurses with more overweight, short sleep duration, and excessive stress levels are at risk of increase blood pressure. This study aims to analyze how the relationship between obesity, nutritional status, sleep duration and stress level influence the blood pressure of the night shift nurses. Materials and methods: The subjects in this study were night shift nurses in four hospitals. The dependent variable was blood pressure and the independent variables were nutritional status, sleep duration, and stress levels. This study was an observational analysis with a perspective cohort design in which the subjects were 312 night shift nurses. Nutritional status were identified from Body Mass Index (BMI) through anthropometric measurement, sleep duration by looking at average hours of sleep during the night service, stress levels through the Perceived Stress Scale (PSS-10) questionnaire. Blood pressure was measured using a mercury sphygmomanometer. Data were analyzed by Chi-square test and Logistic Regression. Results and Discussion: There was a significant relationship between nutritional status, sleep duration, and stress levels with blood pressure. The results of the multivariate analysis showed that the shift nurses with overweight (obesity) nutritional status are at a risk of having disorder 1.97 times, the shift nurses with sleep duration < 6 hours are at risk of having disorder 3.78 times and shift nurses with intermediate stress level at risk of having disorder 2.08 times with enhancement blood pressure. Conclusion: There is a relationship between nutritional status, sleep duration and stress level with blood pressure. Sleep duration mostly influences the blood pressure.


Introduction
Prevalence of hypertension throughout the world at the age of > 18 years is around 22.1% 1 . Indonesia Basic Health Research data (2018) for the age of ≥ 18 years the prevalence of hypertension is higher by 34.1% 2 . Uncontrolled blood pressure causes hypertension and in a long time can cause damage to other body organs such as kidney failure, coronary heart disease and stroke 3 . Blood pressure is not constant that can change in a matter of seconds in which it adjusts the situation or demands of people at that time 4 . Shift work is one of the most obvious sources of disruption for sleep-wake time and has also been shown to increase the risk of cardiovascular disease 5 . Nutritional status is an expression of the state of the body that is affected by certain nutrients. Nutritional status of overweight and obesity can increase degenerative diseases risk, and also the workload of the heart in pumping blood so that hypertension occurs 6 . Overweight can cause an increase in cardiac output because the greater the body mass, the more the amount of blood that circulates so that cardiac output also increases and then, it results in increased blood volume 7 . The benchmark of nutritional status of adults aged > 18 years called Body Mass Index (BMI) according to the standard definition of the Centers for Disease Control (CDC): less weight is less than 18.5 kg/ m 2 , Normal is 18.5-24.9 kg/m 2 , overweight is 25.0-29.9 kg/m 2 , and obesity is ≥ 30.0 kg/m 2 . 8 Blood pressure for 24 hours varies in which normal sleep will reduce blood pressure by 10%. Sleep disorders especially lack of sleep and obstructive sleep apnea are associated with increased blood pressure and the risk of hypertension 9 . Sufficient sleep duration not only maintains bodily functions but also prevents harmful cardiovascular and hypertension effects 10,11 . Increased blood pressure and sympathetic nervous system are caused by limited hours of sleep 12 . Stress is also a cause of increased blood pressure. Stress is a non-specific condition faced by patients due to emotional, physical or environmental demands that exceed the power and ability to cope effectively. Prolonged stress can increase permanent blood pressure 13 . Psychosocial factors show evidence that these factors can play an important role in the occurrence of hypertension. Exposure to the stress of work, stress from social environment, and low socioeconomic status are risk factors for hypertension 14 . All things considered, nutritional status, sleep duration, and stress level can affect health especially to metabolic diseases such as increased blood pressure. In short, it is necessary to conduct further research on night shift nurses working in the hospitals.

Materials and Method
The subjects in this study were night shift nurses working in four hospitals in Bengkulu, Indonesia. The dependent variable was blood pressure and the independent variable was nutritional status, sleep duration, and stress level. The study was observational analytic using perspective cohort design. Therefore, the subjects involved in this study were 312 night shift nurses chosen through random sampling and considered meet the inclusion criteria. This research was conducted from March to July 2019, in 4 hospitals. The subjects agreed to participate as respondents until the study ended and signed informed consent. Nutrition status data were obtained from Body Mass Index (BMI) through anthropometry measurements of body weight and height. Sleep duration was from the Figure 1:Average blood pressure of shift nurses for three months average sleep hours of shift nurses during night shift. Stress levels were obtained through the Indonesian version of the Perceived Stress Scale (PSS-10) questionnaire. Blood pressure was obtained from the blood pressure measurements of the night shift nurses' before they did activities and the measurements used blood pressure tool called sphygmomanometer. Blood pressure was monitored every month for three months during night shift.

Respondent Characteristics
The total of samples was 312, 89.4% of the respondents were 21-30 years old and 10.6% were 31-40 years old. The highest number of sexes were female 84.6% and male ratio was 15.4 %. The initial blood pressure of respondents consisted of normal blood pressure of 132 42.3% and prehypertension of 57.3%. The description of the respondents characteristics is shown in the Table 1.  Figure 1.

The relationship between nutritional status, sleep duration, and stress level with blood pressure
The relationship between nutritional status, sleep duration and stress level with blood pressure is shown in showed that there was significant relationship between nutritional status (p = 0.032) with blood pressure of shift nurse. There was a correlation between sleep duration (p = 0.001) and blood pressure of shift nurse. There was a significant relationship between stress level (p = 0.009) with blood pressure of shift nurses. Analysis results of the relationship between nutritional status, sleep duration, and stress level with blood pressure is shown in Table 3. According to the multivariate analysis (Logistic regression), there is a significant relationship between nutritional status RR = 1.966; p = 0.001, sleep duration RR = 3.776; p =0,021 and stress level RR = 2.075 ; p =0.008 with blood pressure.

Discussion and Conclusion
Based on a chi-square analysis, there is a relationship between nutritional status (overweight and obesity) and blood pressure with p-value (0.032). This study is in line with the studies of Harsha and Bray (2008) and Van et al. (2011) 15.16 , that there is significant relationship between body weight with high blood pressure and there is a direct relationship between being obesity with prehypertension and hypertension. According to the Nurses' Health Study, obesity increases the hypertension risk by 40% and the Framingham Offspring Study states that men are 78% more at risk of developing hypertension than women are at 65%. The relationship between obesity at a young age and permanentobesity status is very at risk of developing hypertension in the future 17,18 . Overweight can cause an increase in cardiac output because the greater the body mass, the more the amount of blood that circulates so that cardiac output also increases and then, it results in an increase in blood volume 7,19. The relationship between obesity nutritional status with hypertension (RR = 1.966) means that nurses with obese nutritional status are 1.97 times at risk of developing hypertension. This is in line with Setyawati's 20 research that there is a relationship between BMI and hypertension. Women having BMI with overweight and obesity categories are 2.05 times more likely to have high blood pressure. Obesity is a risk factor for hypertension with a risk of 2.16 times compared to normal BMI 21 .
Weight gain and hypertension are often reported by night shift nurses as personal health problem. They recognize that being overweight and obesity are common health threats. Besides, some find difficult to cope with the demands of their work 22 . Table 3 shows significant relationship between sleep duration and blood pressure (p = 0.001). This means that sleep duration influences blood pressure for night shift nurse. The risk of an increase in prehypertension and hypertension is caused by sleep duration of fewer than 6 hours 23 . Relationship between sleep duration and blood pressure (RR= 3.776) means that shift nurses with sleep duration is less risk 3.78 times to have increased blood pressure. In agreement with Roshifanni 24 argument that people having poor sleep patterns are 9.02 times more likely to suffer from hypertension compared to people having good sleep patterns. In the contrary 25 stated that short sleep duration is not in respect of the hypertension prevalence occurred in Chinese adult men, but this does not apply anymore if sleep quality categorized poor is possible to be further modified by shift work schedules. Sleep assessment by measuring sleep duration is not enough when exploring the relationship between sleep and hypertension. Hypertension risk is reduced by 0.3207 % when sleep duration increases by 1 hour. The duration of each one-hour extra sleep can reduce hypertension risk by 0.3207% in which shorter sleep greatly affects hypertension 26 . The stress level with blood pressure shown in Table  3 having a significant value (p = 0.009) means that there is a relationship between stress on shift nurses and blood pressure. Relative Risk (RR= 2.075) means that night shift nurses with moderate stress levels have a 1.3 times increased risk of developing blood pressure compared to those with mild stress. This is supported by Suwazono's studies 27,28 showing relatively consistent results pertaining to the relationship between shift work and increased blood pressure. This happens due to particular reason including changes in lifestyle factors caused by circadian rhythm disorder. It can cause mischievous changes in someone's life, for instance, high-stress levels in the form of psychosocial, physiological and behavioral stresses associated with increased risk of cardiovascular diseases such as metabolic syndrome, diabetes, and hypertension 29 . Relationship between job stress with high blood pressure and incidence of CVD has been proven. Work-related variables include shift work schedule or irregular hours and rotating schedule, time pressure, relationships with co-workers, and others. 30 The lack of shift nurses as the cause of stress levels experienced by nurses tends to be high. The workload is increased, because ratio of patients to nurses is unbalanced so that night shift nurses sometimes feel depressed and irritable to create family conflict. Some night shift nurses feel that this work brings work stress and frustration at home. 22,31 Adults spend most of lives at work, so, chronic work stress can have a strong impact on health. The impact of stress on hypertension development is believed to involve the response of sympathetic nervous system where the release of catecholamine causes an increase in blood pressure, heart rate and cardiac output. 14,30 There is a relationship between nutritional statuses, sleep duration and stress level with blood pressure. Sleep duration < 6 hours risky of 3.776 time with the blood pressure on nurse night shift.