REVIEW
The impact of shiftwork on health: a literature review Annabel Matheson, Louise O’Brien and Jo-Anne Reid
Aims and objectives. To identify the impact of shiftwork on individuals and their lives and to discuss the implications this has for nurses and nursing. Background. The context of shiftwork in the early 21st century is changing rapidly, and those involved in or required to work shiftwork are now spread over many different sectors of the community. In the Australian community, 16% of workers regularly work shiftwork. Most nurses undertake shiftwork at some time in their career, and health services could not operate without a shiftworking nursing workforce. Design. Narrative literature review. Methods. A narrative review of journal articles was conducted. Databases searched were CINAHL, EBSCO Host, JSTOR, Medline/PubMed and Google Scholar. Search terms used were ‘shiftwork’ and ‘shift work’. Limitations included ‘English language’, ‘published between 1980–2013’ and ‘human’. Results. Reviewed for this paper were 118 studies that met the inclusion criteria. Results were categorised using thematic analysis. Themes that emerged were physical and psychosocial health, and sleep. Findings will be explored under these themes. Conclusions. Shiftwork research has mainly focussed on the physiological and psychosocial health and sleep effects. Absent from the literature are studies focussing on the personal experience of the shiftworker and how workers mediate the effects of shiftwork and how shiftwork fits into the rest of their lives. Therefore, it is difficult to draw conclusions about how people ‘manage’ their shiftwork, and further research needs to be undertaken in this area. Relevance to clinical practice. Working shifts for nurses is a reality that comes with the profession. While there is a significant body of research on shiftwork, little of this has been specifically applied to nursing, and the implications for individual nurses needing to care for their own health have not been drawn.
What does this paper contribute to the wider global clinical community?
• Provides a review of the litera-
•
ture on shiftwork with emphasis on physical and psychosocial effects. Provides a discussion on the implications of shiftwork for nursing.
Key words: general health, nurses, nursing workforce, review, shift work, shiftwork, sleep Accepted for publication: 27 October 2013
Authors: Annabel Matheson, BN, RN, PhD Candidate, Lecturer, School of Nursing, Midwifery & Indigenous Health, Charles Sturt University, Bathurst; Louise O’Brien, BA, PhD, RN, Professor of Nursing (Mental Health), Centre for Rural and Remote Mental Health, Bloomfield Campus, University of Newcastle and Greater Western Area Health Service, Orange, Adjunct Research Fellow, Charles Sturt University, Bathurst and Adjunct Professor, University of Western Sydney, Orange; Jo-Anne Reid, BA, BEd, PhD, Professor, Associate Dean Teacher Education, Faculty of Education,
© 2014 John Wiley & Sons Ltd Journal of Clinical Nursing, 23, 3309–3320, doi: 10.1111/jocn.12524
Charles Sturt University, Co-editor of Asia-Pacific Journal of Teacher Education, Bathurst and Researcher, Research Institute for Professional Practice, Learning and Education [RIPPLE], Charles Sturt University, Bathurst, NSW, Australia Correspondence: Annabel Matheson, Lecturer, School of Nursing, Midwifery & Indigenous Health, Charles Sturt University, Panorama Ave, Bathurst 2795, NSW, Australia. Telephone: +61 02 6338 4086. E-mail: [email protected]
3309
A Matheson et al.
Introduction The context of shiftwork in the early 21st century is changing rapidly, and in comparison with previous centuries, those involved in or required to work shiftwork are now spread over many different sectors of the community. Industries such as agriculture, telecommunications, printing, health, broadcasting, food production and transport, which are strongly influenced by accelerated urbanisation, also use shiftwork as a means of increasing productivity or for customer service (Frost et al. 2009). With globalisation and the increasing need to conduct work across time zones, workers in industries that traditionally did not use shiftwork such as the banking and finance industry are also now being faced with extended business hours. For the worker, many of the major effects of shiftwork stem from the evolution of humans as a diurnal species (Barton et al. 1995). Until the invention of reasonably effective artificial light sources, humans did not question the natural circadian rhythms of their bodies, even though they were not aware of the physiology involved. Although shiftwork existed long before the invention of the light bulb (Gordon et al. 1986), it was the availability and use of artificial light (commencing with the effective use of lamps and extended by the development of the electric light bulb) that enabled work to be undertaken as long as was either needed or wanted during periods of darkness (Grossman 1997). The advent of the light bulb gradually increased the organisation and use of teams or shifts of workers to continue production after dark. Forges, paper mills, glass works and metallurgical industries were using shiftwork by the 1800s, but the opening of the first power plant in 1882 by Thomas Edison enabled the potential for 24-hour production (Gordon et al. 1986) and formal organisation of shifts for workers. Shiftwork in nursing has had a slightly different historical trajectory. Nursing over the 24-hour time period has been needed since the beginning of time in an informal and then later a more formal capacity. The invention of the light bulb did not change whether babies were born through the night and a midwife was needed or whether people needed round-the-clock nursing for an illness. Nurses, however, are often unaware of their tolerance to the effects of shiftwork, and there is little evidence that managing shiftwork is included in undergraduate nurse education curriculum or in introductory graduate nurse programmes in the workplace.
Aim The aim of this paper is to review the literature pertinent to shiftwork, to identify the effect of shiftwork on the individ-
3310
ual and to discuss the implications these have for nurses and nursing.
Methods The aim of a narrative review is to synthesise the findings of literature retrieved from computerised databases, hand searches and authoritative texts (Green et al. 2006). Databases used in this review included CINAHL, EBSCO Host, JSTOR, Medline/PubMed and Google Scholar. Search terms used were shiftwork and shift work. Use of the word ‘work’ proved problematic for some databases as this retrieved all articles related to general work and these needed further refining to gain access to only shift work articles. Inclusion criteria included human studies (nonanimal), English language, published in a peer-reviewed journal and published between 1980–2013. Exclusion criteria included research focusing on other topics but including shiftwork as a minor keyword (such as studies on work in general) and research that focussed on the organisational perspective. The organisational approach covers issues such as shift system organisation, alertness and vigilance, work accidents and incidents and work errors. These organisational studies are not applicable to the aims of the paper. While being less vigilant due to sleepiness is still the person’s experience of shiftwork, the perspective of organisational research is generally to look at the impact of this on work, rather than on the individual. Duplication of articles between databases was common. All research papers were then appraised for rigour and quality. Ulrich’s database was used to ensure that the research had been published in peer-reviewed journals, although three studies that did not meet this criterion were included. Once the duplicates had been excluded and exclusion criteria had been applied, the final number of reviewed papers was 118. Of the 118 reviewed papers, 109 were from peerreviewed journals, three from expert journals (Journal of Clinical Sleep Medicine & High Blood Pressure & Cardiovascular Prevention), two were reports and four were chapters from a book. Results retrieved from Google Scholar were a variety of types of formats: some were media releases, book chapters or policy statements, many papers retrieved had been published in nonrefereed journals and were therefore excluded. Some papers that were retrieved from Google Scholar were not primarily focussed on shiftwork, but may have mentioned shiftwork in passing and so came up in the search, these were also excluded. Each research paper was organised according to theme. © 2014 John Wiley & Sons Ltd Journal of Clinical Nursing, 23, 3309–3320
Review
The impact of shiftwork on health: a review
Results The literature search revealed the following (Table 1): Shiftwork has been investigated from a variety of perspectives within the literature. There are two approaches from which shiftwork research mainly derives: personal and organisational. Most of the personal research examines the experience and effects of shiftwork on individuals from a variety of perspectives such as sleep, coping and health through means of questionnaires, hormone testing, sleep testing and reaction time tests. The literature related to the personal effects of shiftwork was categorised under several themes: physical health, sleep and psychosocial health.
Findings Physical health One of the most researched areas in the shiftwork literature is the impact on the physical health of the shiftworker. In early research, studies examining the health effects of shiftworkers considered the risks and effects primarily within a symptomatic framework. More recent research has begun deeper investigation of the causal mechanisms behind the symptoms that shiftworkers report (Puttonen et al. 2010). Cardiovascular and gastrointestinal health have been the two major areas of research into the effects of shiftwork, particularly since the definition of the shiftwork maladaptation syndrome in 1985, with symptoms including sleep/ wake disorders, gastrointestinal pathology and an increased risk of cardiovascular disease (Moore-Ede & Richardson 1985). More recently, this syndrome has been known as shiftwork syndrome or shiftwork disorder (Black et al. 2010, Schwartz et al. 2010). Shiftwork disorder is described as a disruption of the circadian sleep/wake cycle, resulting in insomnia, excessive sleepiness and fatigue (Ftouni et al. 2012). More recently, large-scale studies examined increased risk of breast cancer among shiftworkers (Schernhammer et al. 2001, Spiegel & Sephton 2002, Viswanathan Table 1 Results of literature search
Database
Search term ‘Shiftwork’
Search term ‘Shift work’
CINAHL EBSCO Host JSTOR Medline/PubMed Google Scholar
1719 3640 9 349 411
735 244 50,479* 1331 5770*
*High number related to search term ‘work’.
© 2014 John Wiley & Sons Ltd Journal of Clinical Nursing, 23, 3309–3320
& Schernhammer 2009). Other studies on cancers such as endometrial cancers (Viswanathan & Schernhammer 2009) and colorectal cancer have been published (Schernhammer et al. 2003). Sleep and its quality and quantity are other areas that have attracted research effort in the literature. Cardiovascular disease Cardiovascular disease has been studied more comprehensively than other shiftwork-related disorders. Much of this research has been undertaken in Scandinavia, where a team of researchers has been examining the potential effects of shiftwork on the cardiovascular system of shiftworkers for over two decades. This extensive research programme has come to no definitive conclusions however (Boggild 2009, Puttonen et al. 2010). It has been a widely held belief that shiftwork has a detrimental effect on the shiftworker’s cardiovascular system, and morbidity/mortality rates seem to reflect this (Puttonen et al. 2009). This assumption has been further strengthened by a range of research studies in this area; (Karlsson et al. 2001, van Amelsvoort et al. 2004). However, more recent research tends to caution against an absolute causal effect as the evidence seems to be limited (Frost et al. 2009), and some research reports no association between shiftwork and cardiovascular disease (Hublin et al. 2010). The relative risk of cardiovascular disease in men who perform shiftwork has been reported to be 15 times the risk in men who work regular hours during the day (Akerstedt et al. 1984), although risk factors of 064– 225 have been reported (Boggild & Knutsson 1999, Frost et al. 2009), and a higher relative risk has also been suggested in shiftworking women (Kawachi et al. 1995, Knutsson et al. 1999, Ha & Park 2005, Puttonen et al. 2009). Although these relative risks seem low, the nature of their work hours may become a much more significant risk for shiftworkers when combined with other factors known to contribute to cardiovascular disease, such as obesity, poor eating, high caffeine intake and smoking, and for women, when the cardiovascular protective effects of oestrogen cease after menopause or metabolic disorder (Canuto et al. 2013). Rotating night shift work was independently associated with an increased risk of hypertension in black people but not in white people in a longitudinal study drawn from the Nurses’ Health Study II undertaken in USA (Lieu et al. 2012); however, other studies reported no difference between night shift work and day shift work (Burdelak et al. 2012). Increased body mass index was associated with night and rotating shift nurses, but not with permanent day shift nurses in another study (Smith et al. 2013). Other cardiovascular risks such as the development of type 2 diabetes have also been associated with shiftwork.
3311
A Matheson et al.
The causal link or mechanism of action forms much of the recent research effort in the area of cardiovascular disease and shiftwork (van Amelsvoort et al. 1999, Frost et al. 2009). Various studies have examined diet (Knutsson 1989), physiological indicators such as cholesterol (Karlsson et al. 2001), stress (Peter et al. 1999), length of working hours (Sokejima & Kagamimori 1998) and the desynchronisation of circadian rhythms (Knutsson 1989). One theory of the causal link between shiftwork and cardiovascular disease proposes that the sleep loss incurred by shiftworkers is a significant factor because the movement of the circadian rhythms, by either sleep loss or a change in the time of sleep, constitutes a major metabolic challenge to the body (Akerstedt & Knutsson 1997, Frost et al. 2009, Puttonen et al. 2010). This theory encompasses the research that examines inflammation, blood coagulation, cardiac autonomic function and the interaction between cortisol and catecholamine (stress related) and cardiovascular disease (Puttonen et al. 2010). Another premise is that loss of sleep or disturbed sleep affects the immune system, although the exact causal factor here is unknown (Akerstedt & Knutsson 1997). Another hypothesis attributes cardiovascular disease to the effects of a stressful work environment on the cardiovascular system (Akerstedt & Knutsson 1997, Puttonen et al. 2010, Landsbergis et al. 2013). A final theory canvasses the idea that the elevated morbidity/mortality statistics for cardiovascular disease may be directly related to lifestyle factors, such as the type of food eaten and when it is eaten (Frost et al. 2009, Thomas & Power 2010, Nabe-Nielsen et al. 2011) and use of other drugs such as caffeine, alcohol, sleeping aids and other nonprescription drugs (Gordon et al. 1986, Frost et al. 2009). This area has been continuously researched for over two decades, and results are conflicting as to whether shiftwork plays a role in cardiovascular disease.
Gastrointestinal disturbances Gastrointestinal disturbances associated with shiftwork have also been reported in the literature for more than two decades (Sveinsdottir 2006, Burch et al. 2009, Knutsson & Boggild 2010). Symptoms range from dyspepsia, gastritis, colitis and peptic ulcer (Knauth & Harma 1992, Knutsson & Boggild 2010) to indigestion, appetite disturbance (Verhaegen et al. 1987), irregularity of bowel movements, constipation, heartburn, abdominal pains, stomach grumbling, flatulence and gastroduodenitis (Knauth & Harma 1992, Costa 1997). Several factors that may be involved in the other gastrointestinal symptoms reported among shiftworkers include circadian rhythm desynchrony of the gastric
3312
functions (gastric secretion, enzyme activity and intestinal motility) (Costa 1997), types of food consumed (Costa 1997), drug intake (Gordon et al. 1986, Burch et al. 2009), psychosocial stress (Levenstein 1998), and for female shiftworkers, the menstrual cycle (Simmons et al. 1988). The circadian rhythm of gastric acid secretion has not been examined as closely in relation to shiftwork as have other human circadian rhythms (Moore & Halberg 1986). Circadian rhythm desynchrony has been accepted for some time in the shiftwork literature as a significant part of the sleep disturbances related to shiftwork (Akerstedt 1988, Monk 1991, Costa 1997, Howarth et al. 1999, Cruz et al. 2000). Although the symptoms of digestive disturbances have been widely reported, the causal mechanism is not well understood. The available research on the circadian rhythmicity of gastric secretion is more often related to ulceration than to shiftwork. One such study reported that the circadian rhythm of gastric acid secretion entails high rates of acidity during the evening and low levels in the early morning (Moore & Halberg 1986). If these reported low levels of gastric acid secretion counteract efficient digestion during the early hours of the morning, several previously mentioned symptoms might occur. Gastrointestinal function during the menstrual cycle is another element that may confound the data on digestive disturbances or there may be a cumulative effect of shiftwork and the menstrual cycle. Diarrhoea, abdominal pain, nausea and appetite changes have been reported during the premenstrual and menstrual phases of the cycle (Simmons et al. 1988). These symptoms have also been reported in other studies as directly related to shiftwork (Verhaegen et al. 1987, Knauth & Harma 1992, Costa 1997). Other symptoms related to the menstrual cycle include abdominal bloating, weight gain and cramps (Simmons et al. 1988). Although it is difficult to distinguish whether these symptoms are directly related to shiftwork or are in some way related to the menstrual cycle in female shiftworkers, similar symptoms are also reported in male workers. Newer research in the shiftwork area has found impaired glucose metabolism in rotating shift shiftworkers, particularly middle-aged workers (Suwazono et al. 2010) and some evidence of metabolic syndrome in young male shiftworkers ‘due to circadian misalignment’ (Burgueno et al. 2010). No association was reported in another study between metabolic and insulin responses in shift and nonshiftworkers (Wehrens et al. 2010). Yet, another recent study cannot confirm a relationship between shiftwork and upper gastrointestinal, nonspecific gastrointestinal, peptic ulcer or gastritis (van Mark et al. 2010). Rotating shiftwork including night shifts has been associated with © 2014 John Wiley & Sons Ltd Journal of Clinical Nursing, 23, 3309–3320
Review
obesity, metabolic syndrome and glucose dysregulation, and a modest increased risk of type 2 diabetes in women (Pan et al. 2011). Abnormal eating behaviour was positively associated with shiftwork in a recent study conducted on nurses (Wong et al. 2010).
Cancer In 2007, The International Agency for Research on Cancer (Press Release N° 180) stated that ‘shiftwork that involved circadian disruption was probably carcinogenic to humans’ (International Agency for Research on Cancer 2007). The postulated causal mechanism is melatonin suppression by night-time light exposure (Schernhammer et al. 2003, Schwartzbaum et al. 2007, Arendt 2010), increasing levels of oestrogens and growth of hormone-dependant tumours (Schernhammer et al. 2003). Breast cancer risk increased for women where the circadian rhythms of cortisol and prolactin did not adjust when the woman worked shiftwork (Lewy et al. 2007). This study is applied research, and its implications are important for women working shiftwork due to the circadian disruption. Recent research on mechanisms of breast cancer and shiftwork has focussed on the role of melatonin and the impact that night shift has on preventing the rise of this hormone while working (Bhatti et al. 2013). The study postulated that the disruption caused by night shift in the normal rise of melatonin which occurs at night results in higher levels of other reproductive hormones, and this may increase the risk of breast cancer. The authors also theorised that male shiftworkers may also be at a higher risk of prostate cancer due to the same mechanism of increased reproductive hormones (Bhatti et al. 2013). Others have also reported greater risk of breast cancer for those working rotating shifts including night shifts (Hansen & Stevens 2012, Herichova 2013) particularly when they are worked over an extended period of time (Grundy et al. 2011). A study published the same year as the International Agency for Research on Cancer (Press Release N° 180) found no association between breast or prostate cancer and shiftwork (Schwartzbaum et al. 2007), although others dispute this finding based on the limitations of the study (Pukkala & Harma 2007). A recent study reported a strong positive association with shiftwork and elevated prostatespecific antigen levels (Flynn-Evans et al. 2013). A number of large-scale studies examining shiftwork and cancer reported an increased risk of breast cancer among shiftworkers (Davis et al. 2001, Schernhammer et al. 2001, Spiegel & Sephton 2002, Viswanathan & Schernhammer 2009, Hansen & Stevens 2012) although no association © 2014 John Wiley & Sons Ltd Journal of Clinical Nursing, 23, 3309–3320
The impact of shiftwork on health: a review
between breast cancer and shiftwork was found in another study (Pronk et al. 2010), and some argument regarding the methodology of the study has been raised (Girschik et al. 2010). A systematic review and meta-analysis examining night work and breast cancer reported an increased risk for women (Megdal et al. 2005). Other studies linking shiftwork and cancers such as endometrial cancers (Viswanathan & Schernhammer 2009) and colorectal cancer have been published (Schernhammer et al. 2003).
Sleep Sleep has been researched primarily objectively (quantity) and secondarily subjectively (quality). There has also been a research focus on chronic fatigue. Various studies have established that shiftwork affects sleep quality and quantity (Akerstedt et al. 1982, Rutenfranz et al. 1985, Akerstedt 1988, Winwood et al. 2006). The reduction in quantity and quality of sleep is partially related to the need to sleep on schedule at the most inappropriate point in the circadian cycle (Adams et al. 1986). Sleep quantity To study the length of sleep periods or quantity of sleep, instruments such as polysomnography or actigraphy tend to be used (Gale et al. 2005, Morgenthaler et al. 2007) rather than subjective questionnaires. These instruments use computer analysis to determine length of sleep and other sleep characteristics such as mid sleep awakenings and duration of sleep onset. Decreased sleep quantity and quality in male shiftworkers in relation to shiftwork has been established (Rutenfranz et al. 1985, Akerstedt 1988, Sallinen et al. 2003); however, this has not been studied in as much detail in women. More recent studies have tended to focus on women (Florida-James et al. 1996, Cruz et al. 2003, Ha & Park 2005, Garde et al. 2009), filling a previous fairly significant gap in the literature. Longer sleep periods through the day after night shift were reported in one study after exposure to very bright light on night shift (Boivin et al. 2012). The bright light was used to suppress the secretion of melatonin in the low-light settings of some health facilities. While this was reported to assist daytime sleep, it is improbable that it would be used in a majority of shiftwork situations within health care because the promotion of sleep in most settings for the patient/clients is also important. Women, shiftwork and sleep quantity are sometimes explored in relation to other care duties that women need to undertake. The impact of shiftwork on sleep and family life among rotating shift nurses using a time budget method was studied by Kurumatani et al. (1994). This study
3313
A Matheson et al.
showed that sleep was decreased if the subject needed to perform other duties (domestic or otherwise). Instead of sleeping for seven or eight hours when they had time off, family responsibilities were undertaken instead of catching up on their sleep debt (Kurumatani et al. 1994). Other studies have reported decreased sleep quantity when workers have children or elders to care for at home (Clissold et al. 2001, Sallinen et al. 2005, Scott et al. 2006). Insufficient sleep was found to have increased reporting of symptoms such as mental tiredness, exhaustion and altered mood (Edell-Gustafsson et al. 2002, Chan 2009). Sleep quality Sleep quality refers to ‘perceived deep sleep’ (Winwood et al. 2006). Also, sleep quality has been linked with how the individual feels on waking, ease of waking, tiredness, mood, feelings of restoration and refreshment (Harvey et al. 2008). Global sleep quality among permanent night shift nurses was significantly poorer than that of the day shift workers in one study (Ruggiero 2003) and in rotating shift nurses in others (Skipper et al. 1990, Niedhammer et al. 1994, Winwood et al. 2006, Karagozoglu & Bing€ ol 2008, Garde et al. 2009), yet there was no association reported with shift systems in another (Sveinsdottir 2006). Poor sleep quality, higher workload perception, lack of exercise and lack of support were associated with fatigue in an Australian study of aged-care nurses (Samaha et al. 2007). Some shiftworker control over scheduling was trialled to attempt to increase sleep quality, however, no change in sleep quality was reported (Garde et al. 2011). Chronotype (whether someone is naturally an ‘early bird’ or a ‘late owl’) has also been linked to sleep quality on different shifts, rather than shift schedule, in contrast with other studies (Chung et al. 2009). Fatigue Fatigue is a prevalent condition that has often been associated with shiftwork (Akerstedt et al. 1982, Rutenfranz et al. 1985, Josten et al. 2003, McGettrick & O’Neill 2006, Samaha et al. 2007). It is characterised by performance lapses and workers experiencing difficulty keeping their eyes open, and some sleep-like electroencephalography (EEG) patterns may occur (Akerstedt 1988). Chronic fatigue has also been defined as persistent tiredness (Ruggiero 2003, Samaha et al. 2007). Fatigue increased (due to less sleep) when other duties were undertaken (Kurumatani et al. 1994, Clissold et al. 2002, Scott et al. 2006). The literature is unclear as to the exact mechanism of chronic fatigue in shiftwork; one theory is that circadian rhythm desynchrony occurs where sleep is being taken at an inappropriate time in the circadian cycle (Adams et al. 1986); and
3314
another theory proposes that it is the decrease in sleep quantity and/or quality that occurs for many shiftworkers (Kurumatani et al. 1994, Edell-Gustafsson et al. 2002, Ruggiero 2003). The relationship between the amount and quality of sleep for individuals working shiftwork and the impact on the longer term effect of chronic fatigue is unknown. As general consensus has been reached within the shiftwork research area that shiftwork can cause disrupted sleep, the research effort now focuses on finding the best shiftwork system for shiftworkers, and consequently, much of the research reported in this section is over a decade old (Akerstedt et al. 1982, Rutenfranz et al. 1985, Akerstedt 1988).
Psychosocial health One definition of psychosocial health is that it pertains to the influence of social factors on an individual’s mind and behaviour (Martikainen et al. 2002). Shiftwork has been studied in regard to psychosocial health, which can be discussed within two main subtopics: individual and situational differences and personal/work/life experience. Individual and situational differences Domestic circumstances have been primarily examined in terms of impact on sleep for shiftworkers. In two studies, the addition of children to a shiftworking household meant more sleepiness and more domestic disruption (Lushington et al. 1997, Sallinen et al. 2005), particularly for the female shiftworkers (Lushington et al. 1997). Other studies report family-related advantages and disadvantages of shiftwork (Verhaegen et al. 1987, Barton et al. 1993, Smith et al. 1993, Taylor et al. 1997, Strazdins et al. 2006). Several studies examined the reactions and feelings of the partners of shiftworkers (Smith et al. 1993, Newey & Hood 2004, Strazdins et al. 2006). In one study, 53% of participants were unhappy or very unhappy with their partners’ shiftwork, and a third of all respondents had tried to persuade their partners to change their working hours (Smith et al. 1993). This type of research is rare in the body of shiftwork literature, although some research has explored whether partner support helps a worker to better tolerate shiftwork (Robson & Wedderburn 1989). The partners of shiftworkers are a very important group in this context, because domestic disruption is likely to negatively affect the shiftworker’s experience of their work. Another study examined subjective health with shiftwork advantages (Taylor et al. 1997). The results suggested that workers did enjoy some shiftwork advantages, such as a good family life and financial benefits, although the advantages were small (
The impact of shiftwork on health: a literature review Annabel Matheson, Louise O’Brien and Jo-Anne Reid
Aims and objectives. To identify the impact of shiftwork on individuals and their lives and to discuss the implications this has for nurses and nursing. Background. The context of shiftwork in the early 21st century is changing rapidly, and those involved in or required to work shiftwork are now spread over many different sectors of the community. In the Australian community, 16% of workers regularly work shiftwork. Most nurses undertake shiftwork at some time in their career, and health services could not operate without a shiftworking nursing workforce. Design. Narrative literature review. Methods. A narrative review of journal articles was conducted. Databases searched were CINAHL, EBSCO Host, JSTOR, Medline/PubMed and Google Scholar. Search terms used were ‘shiftwork’ and ‘shift work’. Limitations included ‘English language’, ‘published between 1980–2013’ and ‘human’. Results. Reviewed for this paper were 118 studies that met the inclusion criteria. Results were categorised using thematic analysis. Themes that emerged were physical and psychosocial health, and sleep. Findings will be explored under these themes. Conclusions. Shiftwork research has mainly focussed on the physiological and psychosocial health and sleep effects. Absent from the literature are studies focussing on the personal experience of the shiftworker and how workers mediate the effects of shiftwork and how shiftwork fits into the rest of their lives. Therefore, it is difficult to draw conclusions about how people ‘manage’ their shiftwork, and further research needs to be undertaken in this area. Relevance to clinical practice. Working shifts for nurses is a reality that comes with the profession. While there is a significant body of research on shiftwork, little of this has been specifically applied to nursing, and the implications for individual nurses needing to care for their own health have not been drawn.
What does this paper contribute to the wider global clinical community?
• Provides a review of the litera-
•
ture on shiftwork with emphasis on physical and psychosocial effects. Provides a discussion on the implications of shiftwork for nursing.
Key words: general health, nurses, nursing workforce, review, shift work, shiftwork, sleep Accepted for publication: 27 October 2013
Authors: Annabel Matheson, BN, RN, PhD Candidate, Lecturer, School of Nursing, Midwifery & Indigenous Health, Charles Sturt University, Bathurst; Louise O’Brien, BA, PhD, RN, Professor of Nursing (Mental Health), Centre for Rural and Remote Mental Health, Bloomfield Campus, University of Newcastle and Greater Western Area Health Service, Orange, Adjunct Research Fellow, Charles Sturt University, Bathurst and Adjunct Professor, University of Western Sydney, Orange; Jo-Anne Reid, BA, BEd, PhD, Professor, Associate Dean Teacher Education, Faculty of Education,
© 2014 John Wiley & Sons Ltd Journal of Clinical Nursing, 23, 3309–3320, doi: 10.1111/jocn.12524
Charles Sturt University, Co-editor of Asia-Pacific Journal of Teacher Education, Bathurst and Researcher, Research Institute for Professional Practice, Learning and Education [RIPPLE], Charles Sturt University, Bathurst, NSW, Australia Correspondence: Annabel Matheson, Lecturer, School of Nursing, Midwifery & Indigenous Health, Charles Sturt University, Panorama Ave, Bathurst 2795, NSW, Australia. Telephone: +61 02 6338 4086. E-mail: [email protected]
3309
A Matheson et al.
Introduction The context of shiftwork in the early 21st century is changing rapidly, and in comparison with previous centuries, those involved in or required to work shiftwork are now spread over many different sectors of the community. Industries such as agriculture, telecommunications, printing, health, broadcasting, food production and transport, which are strongly influenced by accelerated urbanisation, also use shiftwork as a means of increasing productivity or for customer service (Frost et al. 2009). With globalisation and the increasing need to conduct work across time zones, workers in industries that traditionally did not use shiftwork such as the banking and finance industry are also now being faced with extended business hours. For the worker, many of the major effects of shiftwork stem from the evolution of humans as a diurnal species (Barton et al. 1995). Until the invention of reasonably effective artificial light sources, humans did not question the natural circadian rhythms of their bodies, even though they were not aware of the physiology involved. Although shiftwork existed long before the invention of the light bulb (Gordon et al. 1986), it was the availability and use of artificial light (commencing with the effective use of lamps and extended by the development of the electric light bulb) that enabled work to be undertaken as long as was either needed or wanted during periods of darkness (Grossman 1997). The advent of the light bulb gradually increased the organisation and use of teams or shifts of workers to continue production after dark. Forges, paper mills, glass works and metallurgical industries were using shiftwork by the 1800s, but the opening of the first power plant in 1882 by Thomas Edison enabled the potential for 24-hour production (Gordon et al. 1986) and formal organisation of shifts for workers. Shiftwork in nursing has had a slightly different historical trajectory. Nursing over the 24-hour time period has been needed since the beginning of time in an informal and then later a more formal capacity. The invention of the light bulb did not change whether babies were born through the night and a midwife was needed or whether people needed round-the-clock nursing for an illness. Nurses, however, are often unaware of their tolerance to the effects of shiftwork, and there is little evidence that managing shiftwork is included in undergraduate nurse education curriculum or in introductory graduate nurse programmes in the workplace.
Aim The aim of this paper is to review the literature pertinent to shiftwork, to identify the effect of shiftwork on the individ-
3310
ual and to discuss the implications these have for nurses and nursing.
Methods The aim of a narrative review is to synthesise the findings of literature retrieved from computerised databases, hand searches and authoritative texts (Green et al. 2006). Databases used in this review included CINAHL, EBSCO Host, JSTOR, Medline/PubMed and Google Scholar. Search terms used were shiftwork and shift work. Use of the word ‘work’ proved problematic for some databases as this retrieved all articles related to general work and these needed further refining to gain access to only shift work articles. Inclusion criteria included human studies (nonanimal), English language, published in a peer-reviewed journal and published between 1980–2013. Exclusion criteria included research focusing on other topics but including shiftwork as a minor keyword (such as studies on work in general) and research that focussed on the organisational perspective. The organisational approach covers issues such as shift system organisation, alertness and vigilance, work accidents and incidents and work errors. These organisational studies are not applicable to the aims of the paper. While being less vigilant due to sleepiness is still the person’s experience of shiftwork, the perspective of organisational research is generally to look at the impact of this on work, rather than on the individual. Duplication of articles between databases was common. All research papers were then appraised for rigour and quality. Ulrich’s database was used to ensure that the research had been published in peer-reviewed journals, although three studies that did not meet this criterion were included. Once the duplicates had been excluded and exclusion criteria had been applied, the final number of reviewed papers was 118. Of the 118 reviewed papers, 109 were from peerreviewed journals, three from expert journals (Journal of Clinical Sleep Medicine & High Blood Pressure & Cardiovascular Prevention), two were reports and four were chapters from a book. Results retrieved from Google Scholar were a variety of types of formats: some were media releases, book chapters or policy statements, many papers retrieved had been published in nonrefereed journals and were therefore excluded. Some papers that were retrieved from Google Scholar were not primarily focussed on shiftwork, but may have mentioned shiftwork in passing and so came up in the search, these were also excluded. Each research paper was organised according to theme. © 2014 John Wiley & Sons Ltd Journal of Clinical Nursing, 23, 3309–3320
Review
The impact of shiftwork on health: a review
Results The literature search revealed the following (Table 1): Shiftwork has been investigated from a variety of perspectives within the literature. There are two approaches from which shiftwork research mainly derives: personal and organisational. Most of the personal research examines the experience and effects of shiftwork on individuals from a variety of perspectives such as sleep, coping and health through means of questionnaires, hormone testing, sleep testing and reaction time tests. The literature related to the personal effects of shiftwork was categorised under several themes: physical health, sleep and psychosocial health.
Findings Physical health One of the most researched areas in the shiftwork literature is the impact on the physical health of the shiftworker. In early research, studies examining the health effects of shiftworkers considered the risks and effects primarily within a symptomatic framework. More recent research has begun deeper investigation of the causal mechanisms behind the symptoms that shiftworkers report (Puttonen et al. 2010). Cardiovascular and gastrointestinal health have been the two major areas of research into the effects of shiftwork, particularly since the definition of the shiftwork maladaptation syndrome in 1985, with symptoms including sleep/ wake disorders, gastrointestinal pathology and an increased risk of cardiovascular disease (Moore-Ede & Richardson 1985). More recently, this syndrome has been known as shiftwork syndrome or shiftwork disorder (Black et al. 2010, Schwartz et al. 2010). Shiftwork disorder is described as a disruption of the circadian sleep/wake cycle, resulting in insomnia, excessive sleepiness and fatigue (Ftouni et al. 2012). More recently, large-scale studies examined increased risk of breast cancer among shiftworkers (Schernhammer et al. 2001, Spiegel & Sephton 2002, Viswanathan Table 1 Results of literature search
Database
Search term ‘Shiftwork’
Search term ‘Shift work’
CINAHL EBSCO Host JSTOR Medline/PubMed Google Scholar
1719 3640 9 349 411
735 244 50,479* 1331 5770*
*High number related to search term ‘work’.
© 2014 John Wiley & Sons Ltd Journal of Clinical Nursing, 23, 3309–3320
& Schernhammer 2009). Other studies on cancers such as endometrial cancers (Viswanathan & Schernhammer 2009) and colorectal cancer have been published (Schernhammer et al. 2003). Sleep and its quality and quantity are other areas that have attracted research effort in the literature. Cardiovascular disease Cardiovascular disease has been studied more comprehensively than other shiftwork-related disorders. Much of this research has been undertaken in Scandinavia, where a team of researchers has been examining the potential effects of shiftwork on the cardiovascular system of shiftworkers for over two decades. This extensive research programme has come to no definitive conclusions however (Boggild 2009, Puttonen et al. 2010). It has been a widely held belief that shiftwork has a detrimental effect on the shiftworker’s cardiovascular system, and morbidity/mortality rates seem to reflect this (Puttonen et al. 2009). This assumption has been further strengthened by a range of research studies in this area; (Karlsson et al. 2001, van Amelsvoort et al. 2004). However, more recent research tends to caution against an absolute causal effect as the evidence seems to be limited (Frost et al. 2009), and some research reports no association between shiftwork and cardiovascular disease (Hublin et al. 2010). The relative risk of cardiovascular disease in men who perform shiftwork has been reported to be 15 times the risk in men who work regular hours during the day (Akerstedt et al. 1984), although risk factors of 064– 225 have been reported (Boggild & Knutsson 1999, Frost et al. 2009), and a higher relative risk has also been suggested in shiftworking women (Kawachi et al. 1995, Knutsson et al. 1999, Ha & Park 2005, Puttonen et al. 2009). Although these relative risks seem low, the nature of their work hours may become a much more significant risk for shiftworkers when combined with other factors known to contribute to cardiovascular disease, such as obesity, poor eating, high caffeine intake and smoking, and for women, when the cardiovascular protective effects of oestrogen cease after menopause or metabolic disorder (Canuto et al. 2013). Rotating night shift work was independently associated with an increased risk of hypertension in black people but not in white people in a longitudinal study drawn from the Nurses’ Health Study II undertaken in USA (Lieu et al. 2012); however, other studies reported no difference between night shift work and day shift work (Burdelak et al. 2012). Increased body mass index was associated with night and rotating shift nurses, but not with permanent day shift nurses in another study (Smith et al. 2013). Other cardiovascular risks such as the development of type 2 diabetes have also been associated with shiftwork.
3311
A Matheson et al.
The causal link or mechanism of action forms much of the recent research effort in the area of cardiovascular disease and shiftwork (van Amelsvoort et al. 1999, Frost et al. 2009). Various studies have examined diet (Knutsson 1989), physiological indicators such as cholesterol (Karlsson et al. 2001), stress (Peter et al. 1999), length of working hours (Sokejima & Kagamimori 1998) and the desynchronisation of circadian rhythms (Knutsson 1989). One theory of the causal link between shiftwork and cardiovascular disease proposes that the sleep loss incurred by shiftworkers is a significant factor because the movement of the circadian rhythms, by either sleep loss or a change in the time of sleep, constitutes a major metabolic challenge to the body (Akerstedt & Knutsson 1997, Frost et al. 2009, Puttonen et al. 2010). This theory encompasses the research that examines inflammation, blood coagulation, cardiac autonomic function and the interaction between cortisol and catecholamine (stress related) and cardiovascular disease (Puttonen et al. 2010). Another premise is that loss of sleep or disturbed sleep affects the immune system, although the exact causal factor here is unknown (Akerstedt & Knutsson 1997). Another hypothesis attributes cardiovascular disease to the effects of a stressful work environment on the cardiovascular system (Akerstedt & Knutsson 1997, Puttonen et al. 2010, Landsbergis et al. 2013). A final theory canvasses the idea that the elevated morbidity/mortality statistics for cardiovascular disease may be directly related to lifestyle factors, such as the type of food eaten and when it is eaten (Frost et al. 2009, Thomas & Power 2010, Nabe-Nielsen et al. 2011) and use of other drugs such as caffeine, alcohol, sleeping aids and other nonprescription drugs (Gordon et al. 1986, Frost et al. 2009). This area has been continuously researched for over two decades, and results are conflicting as to whether shiftwork plays a role in cardiovascular disease.
Gastrointestinal disturbances Gastrointestinal disturbances associated with shiftwork have also been reported in the literature for more than two decades (Sveinsdottir 2006, Burch et al. 2009, Knutsson & Boggild 2010). Symptoms range from dyspepsia, gastritis, colitis and peptic ulcer (Knauth & Harma 1992, Knutsson & Boggild 2010) to indigestion, appetite disturbance (Verhaegen et al. 1987), irregularity of bowel movements, constipation, heartburn, abdominal pains, stomach grumbling, flatulence and gastroduodenitis (Knauth & Harma 1992, Costa 1997). Several factors that may be involved in the other gastrointestinal symptoms reported among shiftworkers include circadian rhythm desynchrony of the gastric
3312
functions (gastric secretion, enzyme activity and intestinal motility) (Costa 1997), types of food consumed (Costa 1997), drug intake (Gordon et al. 1986, Burch et al. 2009), psychosocial stress (Levenstein 1998), and for female shiftworkers, the menstrual cycle (Simmons et al. 1988). The circadian rhythm of gastric acid secretion has not been examined as closely in relation to shiftwork as have other human circadian rhythms (Moore & Halberg 1986). Circadian rhythm desynchrony has been accepted for some time in the shiftwork literature as a significant part of the sleep disturbances related to shiftwork (Akerstedt 1988, Monk 1991, Costa 1997, Howarth et al. 1999, Cruz et al. 2000). Although the symptoms of digestive disturbances have been widely reported, the causal mechanism is not well understood. The available research on the circadian rhythmicity of gastric secretion is more often related to ulceration than to shiftwork. One such study reported that the circadian rhythm of gastric acid secretion entails high rates of acidity during the evening and low levels in the early morning (Moore & Halberg 1986). If these reported low levels of gastric acid secretion counteract efficient digestion during the early hours of the morning, several previously mentioned symptoms might occur. Gastrointestinal function during the menstrual cycle is another element that may confound the data on digestive disturbances or there may be a cumulative effect of shiftwork and the menstrual cycle. Diarrhoea, abdominal pain, nausea and appetite changes have been reported during the premenstrual and menstrual phases of the cycle (Simmons et al. 1988). These symptoms have also been reported in other studies as directly related to shiftwork (Verhaegen et al. 1987, Knauth & Harma 1992, Costa 1997). Other symptoms related to the menstrual cycle include abdominal bloating, weight gain and cramps (Simmons et al. 1988). Although it is difficult to distinguish whether these symptoms are directly related to shiftwork or are in some way related to the menstrual cycle in female shiftworkers, similar symptoms are also reported in male workers. Newer research in the shiftwork area has found impaired glucose metabolism in rotating shift shiftworkers, particularly middle-aged workers (Suwazono et al. 2010) and some evidence of metabolic syndrome in young male shiftworkers ‘due to circadian misalignment’ (Burgueno et al. 2010). No association was reported in another study between metabolic and insulin responses in shift and nonshiftworkers (Wehrens et al. 2010). Yet, another recent study cannot confirm a relationship between shiftwork and upper gastrointestinal, nonspecific gastrointestinal, peptic ulcer or gastritis (van Mark et al. 2010). Rotating shiftwork including night shifts has been associated with © 2014 John Wiley & Sons Ltd Journal of Clinical Nursing, 23, 3309–3320
Review
obesity, metabolic syndrome and glucose dysregulation, and a modest increased risk of type 2 diabetes in women (Pan et al. 2011). Abnormal eating behaviour was positively associated with shiftwork in a recent study conducted on nurses (Wong et al. 2010).
Cancer In 2007, The International Agency for Research on Cancer (Press Release N° 180) stated that ‘shiftwork that involved circadian disruption was probably carcinogenic to humans’ (International Agency for Research on Cancer 2007). The postulated causal mechanism is melatonin suppression by night-time light exposure (Schernhammer et al. 2003, Schwartzbaum et al. 2007, Arendt 2010), increasing levels of oestrogens and growth of hormone-dependant tumours (Schernhammer et al. 2003). Breast cancer risk increased for women where the circadian rhythms of cortisol and prolactin did not adjust when the woman worked shiftwork (Lewy et al. 2007). This study is applied research, and its implications are important for women working shiftwork due to the circadian disruption. Recent research on mechanisms of breast cancer and shiftwork has focussed on the role of melatonin and the impact that night shift has on preventing the rise of this hormone while working (Bhatti et al. 2013). The study postulated that the disruption caused by night shift in the normal rise of melatonin which occurs at night results in higher levels of other reproductive hormones, and this may increase the risk of breast cancer. The authors also theorised that male shiftworkers may also be at a higher risk of prostate cancer due to the same mechanism of increased reproductive hormones (Bhatti et al. 2013). Others have also reported greater risk of breast cancer for those working rotating shifts including night shifts (Hansen & Stevens 2012, Herichova 2013) particularly when they are worked over an extended period of time (Grundy et al. 2011). A study published the same year as the International Agency for Research on Cancer (Press Release N° 180) found no association between breast or prostate cancer and shiftwork (Schwartzbaum et al. 2007), although others dispute this finding based on the limitations of the study (Pukkala & Harma 2007). A recent study reported a strong positive association with shiftwork and elevated prostatespecific antigen levels (Flynn-Evans et al. 2013). A number of large-scale studies examining shiftwork and cancer reported an increased risk of breast cancer among shiftworkers (Davis et al. 2001, Schernhammer et al. 2001, Spiegel & Sephton 2002, Viswanathan & Schernhammer 2009, Hansen & Stevens 2012) although no association © 2014 John Wiley & Sons Ltd Journal of Clinical Nursing, 23, 3309–3320
The impact of shiftwork on health: a review
between breast cancer and shiftwork was found in another study (Pronk et al. 2010), and some argument regarding the methodology of the study has been raised (Girschik et al. 2010). A systematic review and meta-analysis examining night work and breast cancer reported an increased risk for women (Megdal et al. 2005). Other studies linking shiftwork and cancers such as endometrial cancers (Viswanathan & Schernhammer 2009) and colorectal cancer have been published (Schernhammer et al. 2003).
Sleep Sleep has been researched primarily objectively (quantity) and secondarily subjectively (quality). There has also been a research focus on chronic fatigue. Various studies have established that shiftwork affects sleep quality and quantity (Akerstedt et al. 1982, Rutenfranz et al. 1985, Akerstedt 1988, Winwood et al. 2006). The reduction in quantity and quality of sleep is partially related to the need to sleep on schedule at the most inappropriate point in the circadian cycle (Adams et al. 1986). Sleep quantity To study the length of sleep periods or quantity of sleep, instruments such as polysomnography or actigraphy tend to be used (Gale et al. 2005, Morgenthaler et al. 2007) rather than subjective questionnaires. These instruments use computer analysis to determine length of sleep and other sleep characteristics such as mid sleep awakenings and duration of sleep onset. Decreased sleep quantity and quality in male shiftworkers in relation to shiftwork has been established (Rutenfranz et al. 1985, Akerstedt 1988, Sallinen et al. 2003); however, this has not been studied in as much detail in women. More recent studies have tended to focus on women (Florida-James et al. 1996, Cruz et al. 2003, Ha & Park 2005, Garde et al. 2009), filling a previous fairly significant gap in the literature. Longer sleep periods through the day after night shift were reported in one study after exposure to very bright light on night shift (Boivin et al. 2012). The bright light was used to suppress the secretion of melatonin in the low-light settings of some health facilities. While this was reported to assist daytime sleep, it is improbable that it would be used in a majority of shiftwork situations within health care because the promotion of sleep in most settings for the patient/clients is also important. Women, shiftwork and sleep quantity are sometimes explored in relation to other care duties that women need to undertake. The impact of shiftwork on sleep and family life among rotating shift nurses using a time budget method was studied by Kurumatani et al. (1994). This study
3313
A Matheson et al.
showed that sleep was decreased if the subject needed to perform other duties (domestic or otherwise). Instead of sleeping for seven or eight hours when they had time off, family responsibilities were undertaken instead of catching up on their sleep debt (Kurumatani et al. 1994). Other studies have reported decreased sleep quantity when workers have children or elders to care for at home (Clissold et al. 2001, Sallinen et al. 2005, Scott et al. 2006). Insufficient sleep was found to have increased reporting of symptoms such as mental tiredness, exhaustion and altered mood (Edell-Gustafsson et al. 2002, Chan 2009). Sleep quality Sleep quality refers to ‘perceived deep sleep’ (Winwood et al. 2006). Also, sleep quality has been linked with how the individual feels on waking, ease of waking, tiredness, mood, feelings of restoration and refreshment (Harvey et al. 2008). Global sleep quality among permanent night shift nurses was significantly poorer than that of the day shift workers in one study (Ruggiero 2003) and in rotating shift nurses in others (Skipper et al. 1990, Niedhammer et al. 1994, Winwood et al. 2006, Karagozoglu & Bing€ ol 2008, Garde et al. 2009), yet there was no association reported with shift systems in another (Sveinsdottir 2006). Poor sleep quality, higher workload perception, lack of exercise and lack of support were associated with fatigue in an Australian study of aged-care nurses (Samaha et al. 2007). Some shiftworker control over scheduling was trialled to attempt to increase sleep quality, however, no change in sleep quality was reported (Garde et al. 2011). Chronotype (whether someone is naturally an ‘early bird’ or a ‘late owl’) has also been linked to sleep quality on different shifts, rather than shift schedule, in contrast with other studies (Chung et al. 2009). Fatigue Fatigue is a prevalent condition that has often been associated with shiftwork (Akerstedt et al. 1982, Rutenfranz et al. 1985, Josten et al. 2003, McGettrick & O’Neill 2006, Samaha et al. 2007). It is characterised by performance lapses and workers experiencing difficulty keeping their eyes open, and some sleep-like electroencephalography (EEG) patterns may occur (Akerstedt 1988). Chronic fatigue has also been defined as persistent tiredness (Ruggiero 2003, Samaha et al. 2007). Fatigue increased (due to less sleep) when other duties were undertaken (Kurumatani et al. 1994, Clissold et al. 2002, Scott et al. 2006). The literature is unclear as to the exact mechanism of chronic fatigue in shiftwork; one theory is that circadian rhythm desynchrony occurs where sleep is being taken at an inappropriate time in the circadian cycle (Adams et al. 1986); and
3314
another theory proposes that it is the decrease in sleep quantity and/or quality that occurs for many shiftworkers (Kurumatani et al. 1994, Edell-Gustafsson et al. 2002, Ruggiero 2003). The relationship between the amount and quality of sleep for individuals working shiftwork and the impact on the longer term effect of chronic fatigue is unknown. As general consensus has been reached within the shiftwork research area that shiftwork can cause disrupted sleep, the research effort now focuses on finding the best shiftwork system for shiftworkers, and consequently, much of the research reported in this section is over a decade old (Akerstedt et al. 1982, Rutenfranz et al. 1985, Akerstedt 1988).
Psychosocial health One definition of psychosocial health is that it pertains to the influence of social factors on an individual’s mind and behaviour (Martikainen et al. 2002). Shiftwork has been studied in regard to psychosocial health, which can be discussed within two main subtopics: individual and situational differences and personal/work/life experience. Individual and situational differences Domestic circumstances have been primarily examined in terms of impact on sleep for shiftworkers. In two studies, the addition of children to a shiftworking household meant more sleepiness and more domestic disruption (Lushington et al. 1997, Sallinen et al. 2005), particularly for the female shiftworkers (Lushington et al. 1997). Other studies report family-related advantages and disadvantages of shiftwork (Verhaegen et al. 1987, Barton et al. 1993, Smith et al. 1993, Taylor et al. 1997, Strazdins et al. 2006). Several studies examined the reactions and feelings of the partners of shiftworkers (Smith et al. 1993, Newey & Hood 2004, Strazdins et al. 2006). In one study, 53% of participants were unhappy or very unhappy with their partners’ shiftwork, and a third of all respondents had tried to persuade their partners to change their working hours (Smith et al. 1993). This type of research is rare in the body of shiftwork literature, although some research has explored whether partner support helps a worker to better tolerate shiftwork (Robson & Wedderburn 1989). The partners of shiftworkers are a very important group in this context, because domestic disruption is likely to negatively affect the shiftworker’s experience of their work. Another study examined subjective health with shiftwork advantages (Taylor et al. 1997). The results suggested that workers did enjoy some shiftwork advantages, such as a good family life and financial benefits, although the advantages were small (
