Shift Work and the Prevalence of Chronic Diseases in Nurses
Introduction
Working time, sleep and diet composition are closely linked to lifestyle. Today’s ,,round-the-clock‘‘ (active) lifestyle is possible 24 hours a day, 7 days a week. This way of life is largely made possible by artificial lighting, which has reduced human dependence on daylight. This progress contributed to the extension of normal working time and to night shifts. In modern society, shift work is one of the most widespread types of occupation, affecting 15 to 20% of the working population in Europe (Peplonska, 2015, Wang, 2011). However, shift work is difficult to define because non-standard working time includes several types of scheduling. Under the Labour Code, shift work is defined as a part of statutory weekly working time that an employee is required to work according to a pre-set shift schedule (Act No. 311/2001 Z. z.). Shift working time is generally a potential health hazard. Partly this is caused by disruption of the rhythm of the body clock, when there is a change in the circadian organization of physiological, endocrine, metabolic and social processes. The body therefore develops a physiological response to circadian stress.
Shift work is encountered in various professions, and one of them is healthcare. Continuous inpatient care is provided in three-shift operation or continuous operation, in two-shift operation and on-site standby at the workplace, or work in one-shift operation with on-site standby, while the above work patterns can also be supplemented by on-call duty at an agreed location outside the workplace. Nurses and midwives working night shifts have their total weekly working time set by legal regulations in the Slovak Republic (SR). Nurses as healthcare providers under § 27(1) of Act No. 578/2004 Z. z. on providers of healthcare, healthcare workers, and professional organizations in healthcare (hereinafter the “act on providers”) perform work in an unevenly arranged work schedule, usually with a working-time length of 11–12 hours (10.5–11 hours of working time, with a half-hour break or two half-hour breaks) (Act No. 311/2001 Z. z. Labour Code).
In unevenly scheduled working time, healthcare workers (doctor, nurse) experience chronic shortening of sleep duration. Sleep is among the fundamental pillars (diet + physical activity + sleep) of a healthy lifestyle. The importance of the physiological need for sleep is promoted at the scientific level and sleep of optimal length and quality has an irreplaceable role for a person. Due to chronic exposure to short sleep as a result of night work, chronic disturbances and changes in food intake develop in the body. Tolerance of sleep deprivation, as well as the need for sleep itself, is, however, highly individual.
Sleep is a basic physiological need, described as a state of rest, free motor inactivity and relaxation (Černák, 2009). To an important extent, it contributes to overall health and quality of life for every person. Regulation of the sleep-wake cycle is controlled by the paired SCN (suprachiasmatic nuclei) located in the hypothalamus. The suprachiasmatic nuclei are responsible for maintaining circadian rhythms throughout the entire body (Table 1). They respond to external stimuli (light-dark alternation) and influence hormone production, especially melatonin, the main hormone determining circadian rhythm (Nevšímalová, 2007).
Current epidemiological studies present evidence of relationships between sleep duration and its quality with unfavorable health consequences. Major disruptors of sleep among nurses working shifts include anxiety, stress, and depression (Bidulescu et al., 2010), as well as chronic diseases (especially of the respiratory, cardiovascular and musculoskeletal systems) (Buxton et al., 2010).
Errors/Mistakes in relation to shift work
Disruption of circadian rhythmicity of the sleep cycle in nurses in relation to working time, stress, and poor lifestyle leads to increased risks of making errors during the night shift.
Niu et al. (2012) in a randomized clinical study found that nurses working night shifts made 44 times more errors than nurses working in daytime shift work. Possible causes of errorfulness are related to fatigue or sleep deprivation.
Table 1 Relationship of Hormones to Sleep and Circadian Rhythms
The occurrence of selected chronic diseases in relation to shift work Gastrointestinal tract (GIT)
Light and daytime food intake are significant environmental factors influencing everyday life. Among healthcare workers working in shift systems, gastrointestinal problems are among the most frequent health problems (Černák, 2009). Nurses most often suffer symptoms of digestive complaints, namely: diarrhea, constipation, bloating, regurgitation, heartburn, and black tarry stool (Saberi et al., 2010).
With respect to shift work, irritable bowel syndrome (IBS) has significantly higher prevalence among nurses working night shifts, compared with nurses working in single-shift operation and nurses in operating theatres (Nojkov, 2010).
Cardiovascular system (CVD)
The incidence of cardiovascular diseases (diagnosed myocardial infarction, angina pectoris, hypertension) is significantly higher in the group of nurses working night shifts (Kivimäki et al., 2006). In many epidemiological studies, we also find a relationship between cardiovascular diseases and the occurrence of metabolic syndrome (MS). According to the World Health Organisation (WHO), cardiovascular diseases are the most common cause of death in the civilized world, and the presence of MS increases the mortality risk 2-fold for CVD (Mottilio et al., 2010).
Metabolic syndrome
(MS) was first described by Reaven in 1988 as a combination of insulin resistance, hypertriglyceridemia, HDL cholesterol and hypertension (Svačina, 2006). The International Diabetes Federation (IDF) emphasizes the importance of central obesity as a core factor and defines MS as the presence of central obesity (waist circumference > 94 (resp. 80) cm in men (resp. women) and two of the following factors: triglycerides (TG) > 1.70 mmol/l, HDL cholesterol (HDL-C) < 1.04 (resp. < 1.30) mmol/l in men (resp. women), blood pressure > 130/85 mm Hg (or antihypertensive treatment), and impaired fasting glycemia (glycaemia > 5.6 mmol/l) or presence of DM2 (Krahulec, 2002).
The relationship between shift work and development of metabolic syndrome was observed in 226 Korean nurses aged 19–49 years. The study showed significantly higher MS prevalence among nurses older than 30 years working night shifts compared with nurses in daytime shift work. A significant dependence was found with waist circumference, HDL and TKd as risk factors (Ha, 2005). Increased intake of sweetened beverages and sleep duration in relation to night work significantly correlated with higher BMI among Japanese nurses (Tada et al., 2014).
In the American 10-year Nurses Health Study II, about 60,000 nurses aged 29–46 years were followed. Increased risk of chronic disease diabetes mellitus type 2 (DM2) was significant among nurses with sleep duration shorter than 5 hours compared with nurses whose sleep duration was 7–8 hours. The study’s results also confirmed increasing disease risk with increasing years of work and night shifts (Kroenke et al., 2007).
Conclusion
Sleep is important for brain regeneration, restoring mental energy, and at the same time plays an important role in substance metabolism and the proper functioning of the endocrine, immune and cardiovascular systems. Long-term insufficient sleep or low sleep quality leads to the development of many diseases. Despite these facts, the priority of every healthcare professional is always the protection and support of their own health and patient safety.
Good health literacy of nurses regarding the effect of disturbed sleep quality and duration in relation to shift work is primary prevention aimed at maintaining good health. Employer interventions are also highly significant by implementing strategic measures to monitor the balance between work and private life in nurses.
Autori: PhDr. Gabriela Štefková, PhD., PhDr. Valéria Parová, PhD. Univerzita Pavla Jozefa Šafárika, Lekárska fakulta, Ústav ošetrovateľstva Zoznam bibliografických odkazov BARANCOVÁ, H. Labour Code. Commentary. Prague, C. H. Beck, 2010.
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Act No. 311/2001 Z. z. Labour Code in the wording of later amendments.
Act No. 578/2004 Z. z. on providers of healthcare, healthcare workers, and professional organizations in healthcare.