Marie-Anne Gautier^[1]

Atypical working hours can be described as any ‘form of work organisation wherein work is carried out on a staggered basis outside the framework of the standard week’. This includes night work and shift work, as well as the other forms of schedules discussed in a previous chapter by Laurence Weibel. There is, however, another category of working hours that is a little different: long hours. These schedules have been studied for several decades in South-East Asia because of their frequency and their effects on health. Indeed, the culture of excessive work, with working hours of more than 45 hours per week, is widespread there: in 2013, 23% of Japanese middle-class employees worked more than 50 hours per week (ILO, 2014). The syndrome of sudden death due to overwork, or Karoshi, was first studied and described in Japan in the 1970s (Egushi et al., 2016). However, in recent years, the practice of long working hours has been constantly evolving in Europe and in France, apparently owing to a strong social and economic demand.

1. Definition and background

In 2009, the DARES (Direction of Support to Research and Statistical Studies, at the French Ministry of Labour) formalised a typology of six occupational groups according to their working hours. Only one category is identified as having ‘normal or standard hours’, representing only 37% of all workers. The other five categories correspond to ‘atypical’ working hours, including the category of ‘those whose hours are long, flexible and not very constrained, such as managers, who often work after hours without this being imposed on them’ (Bué and Coutrot, 2009).

In Europe, Council Directive 93/104/EC of 23 November,1993, amended by the European Parliament and the Council’s Directive 2000/34/EC of 22 June, 2000, defines ‘working time’, ‘resting periods’ and ‘night time’ for all EU member states. It limits the weekly working time to an average of 48 hours. This delimitation is used as a reference for many studies that investigate the health effects of long working hours. However, a working week of 40 hours or more is often considered to characterise long hours.

In practice, within the European Union, the average weekly working time for full-time employees is estimated at 40.3 hours. In France, in 2018, it ranged from 37.1 to 39.1 hours per week (Insee, 2018; Letroublon and Zilloniz, 2018). More recently, in 2019, the SUMER survey found that around 20% of the employees surveyed had worked more than 40 hours during the week before the survey and that these employees were mainly managers and intellectual professionals.

Among these organisations, it is important to differentiate between ‘long working hours’ and those practised in the double 12-hour-shift system (also called ‘long shifts’). These are schedules set by a strict organisation of working time and include both daytime and nighttime hours (Weibel et al, 2014). These long schedules are to be distinguished from ‘long working hours’, which have no fixed organisational framework and do not necessarily include night periods, but which correspond to flexible schedules linked to the habits and workload of the employees who do them. This distinction echoes the one by Costa et al. (2006), mentioned in a previous chapter on atypical working hours, which distinguishes between two forms of flexibility: ‘variability’, when flexibility is determined by employers, and ‘flexibility’, when the employee has control over its hours.

In South-East Asian countries, this widespread practice of long working hours is linked to specific cardiovascular pathologies, such as the Karoshi syndrome, or sudden death due to overwork (Egushi et al., 2016). However, recent bibliographical research shows that long working hours seem not only to cause other health effects, psychological disorders in particular, but also to foster addictions, alterations in overall health, and even abnormalities during pregnancy.

Based on a review of the literature, this article summarises current knowledge on the health effects of long working hours. Nevertheless, it has been found that the various documents selected (scientific articles, expert reports, literature reviews) frequently suffer from methodological weaknesses in the characterisation of exposure to long hours. Indeed, in the vast majority of studies, only the length of the working week is specified, while the characteristics of this working time (in particular, the presence of other types of hourly organisation, such as night work, staggered work, etc.) are left undefined and unspecified.

2. Cardiovascular effects known for several decades

In South-East Asian countries, long hours are very common and are suspected to be the cause of the Karoshi syndrome. This syndrome results in sudden deaths, more than 60% of which are thought to be due to strokes and only 10% to myocardial infarction (Nishiyama and Johnson, 1997; Iwasaki et al., 2006).

Numerous research studies have sought to identify causal relationships between long hours and cardio- and cerebrovascular disease. In 2012, a comprehensive literature review and meta-analysis found a high level of evidence for an association between long working hours and coronary heart disease. This review, based on 12 studies selected for their scientific quality and involving 22,518 participants, showed that the risk of coronary heart disease was about 40% higher in employees exposed to long working hours (Virtanen et al., 2012).

Another large-scale epidemiological study found an increased risk of stroke for employees with long working days, with the risk increasing in proportion to the length of the working week. It also found a risk of coronary events, but estimated to be more moderate (Kivimaki et al., 2015). These results were confirmed by a recent study carried out using the French CONSTANCES cohort. It showed that there was an increased risk of stroke when employees were exposed to these long hours (more than 10 hours per day, 50 days per year) for more than 10 years (Fadel et al., 2019).

Long working hours are also suspected to be a cause of increased blood pressure. In a study of a sample of service sector employees (3,547 white-collar workers followed for five years), long working hours were identified as an independent risk factor for high blood pressure, even after adjusting for confounding factors, such as socioeconomic conditions, diabetes, medical history, and psychosocial risk factors (Trudel et al, 2019).

However, these results must be balanced. Indeed, other studies minimise them, as in the case of Virtanen’s Swedish team, which, in a new review of the literature, showed a more moderate link between the incidence of coronary heart disease and strokes and long working long hours in excess of 55 hours per week. In the conclusion, the authors suggest that further research is needed to clarify the contribution of individual factors, such as stress sensitivity, the presence of atherosclerosis, or abnormalities in glycaemic control, to the development of these conditions (Virtanen and Kivimäki, 2018). In 2013, a study with two groups of Korean workers found an ‘excess risk’ in the group of those who had worked more than 60 hours, but also in the group of workers who had what were considered normal working hours (less than 40 hours per week) (Jeong et al., 2013). Finally, in Denmark, a recent 2018 study found no evidence of a causal relationship between the presence of ischaemic pathology and long working hours, or between taking blood pressure medication and long working hours (Hannerz, 2018).

Long working hours are also suspected to be a cause of metabolic syndrome^[2]. In 2009, a Japanese study on a population of blue-collar workers found a higher risk of metabolic syndrome in those who worked more than 10 hours a day (even when not in shifts). This risk increased with age (Kobayashi et al., 2012). However, these results must be balanced, as other studies have found the same for teams working in shifts (three 8-hour shifts or two 12-hour shifts), and therefore probably also at night. The incidence of long hours in these studies is therefore difficult to ascertain (Oh and Yim, 2017; Pimenta, 2015).

Working long hours would also be significantly and proportionally correlated with overweight (measured in terms of increased body mass index), as recently highlighted by Zhu in a meta-analysis of 259 articles (Zhu, 2019).

3. Other than cardiovascular effects

Long working hours are suspected to cause other effects and pathologies besides cardiovascular ones.

For example, a major literature review in 2014 by Bannai and Tamakoshi (2014) showed that exposure to long working hours caused many health effects. In this work, the schedule exposure was quite specific: a duration of more than eight hours per day or more than 40 hours per week, strictly excluding night work. After analysing the results, the authors concluded that exposure to these long hours represented an increased risk of coronary heart disease, but also of depression, anxiety, and sleep difficulties.

Indeed, long working hours often have consequences for mental and psychic health.

In Australia, between 2001 and 2012, a large survey of families within the HILDA (Household, Income and Labour Dynamics in Australia) cohort collected data regarding their economic and social well-being, and their work and family experiences. The results showed that the groups with the longest working hours (49-59 hours and more than 60 hours per week) had ‘poor’ mental health on the Short Form (36) Health Survey (SF-36), especially among women who worked 49-59 hours per week. This deterioration in mental health status was also more marked when the level of qualification was high (Milner et al., 2015).

Numerous studies relate long working hours to the occurrence of psychological disorders, such as anxiety and depression. For example, in Great Britain, in a population of police officers, statistically significant links were found between long working hours (more than 49 hours per week) and the presence of psychological distress, emotional exhaustion, and depersonalisation (Houdmont and Randall, 2016). Another epidemiological study showed that domestic workers working more than 55 hours per week had a higher risk of developing depressive and anxiety symptoms, especially if they were women (Virtanen et al., 2011). In a population of Japanese medical students, it was found that those who worked between 80 and 99.9 hours per week, and those who worked 100 hours or more, had a higher risk of developing depression than those who worked less than 60 hours per week (Ogawa et al., 2018). Also in Japan, in a population of teachers, the presence of depressive symptoms was found in men who worked more than 50 hours per week (Bannai, 2015).

Long working hours are also suspected to be a cause of sleep disorders and their consequences. In a Korean study (Park, 2001), chronic fatigue was linked to long working hours (from less than 60 hours to more than 70 hours per week) in workers who were questioned about their practices (hours of sleep, physical exercise, alcohol consumption, medical history and conditions, use of medication, sleepiness, lethargy, and concentration difficulties), as well as their occupational stress. Excessive sleepiness was also found in a US study (Arbour et al., 2019), which showed significant alterations in Epworth scale scores in midwives working more than 12 hours a day (without specifying whether they were doing night work).

Long working hours may also entail an increase in alcohol consumption. The results of a meta-analysis (from 61 studies in 14 countries) showed an increased risk of alcohol consumption among people (33,693 participants) working between 49 and 55 hours and those who worked more than 55 hours per week (Virtanen, 2015).

Finally, long working hours may be a factor in the suicide of adult males in Japan. Long working hours appear to be a more important risk factor for suicide than other factors, such as low pay, lack of leisure activities, and lack of hobbies (Takeuchi et al., 2014).

Working long hours could also affect the use and access to care, as well as the general health: working more than 60 hours a week for employees aged 20 to 54 would result in dissatisfaction with access to healthcare, becoming therefore detrimental to their health (Seok et al., 2016). An analysis of health data self-reported by workers aged 25-64 years found an increased risk of ‘impaired health’ among employees working more than 60 hours per week (Song et al., 2014).

The presence of chronic musculoskeletal pain in a population of Japanese workers was related to working more than nine hours per day.In contrast, this risk was mitigated when their daily amount of sleep exceeded seven hours per day (Ando et al., 2019).

For women, gynaecological consequences are mentioned, since long working hours could also have an effect on pregnancy and its progress. Research in the United States found that women who worked more than 40 hours per week had a significant risk of miscarriage, preterm delivery, or having a low weight or sized baby. The results also showed that the risk of preterm delivery was increased by 10% when the weekly working time exceeded 55 hours (Chenxi et al., 2019). Working schedules (of more than 60 hours per week) could also disrupt the regularity of menstrual cycles. (Ok et al., 2019).

Conclusion

Long working hours have been studied for several decades in South-East Asia because of their widespread occurrence due to socio-cultural reasons. They are also beginning to be studied in Western countries because of their expansion.

There are two main types: those that are fixed by a strict organisation of working time and imposed by the organisation, such as the two weekly 12-hour shifts, and those that have no fixed framework: flexible hours linked to the habits and workload of the employees. These are, for example, the hours self-willingly worked by ‘managers’, who choose them informally to ensure a better reconciliation between their personal and professional lives, thus ‘absorbing’ their work overload (Bué and Coutrot, 2009). Finally, the practice of pluriactivity can also be the cause of long working hours.

It is difficult to investigate their effects on health because of the many methodological problems involved. Indeed, exposure to long hours is often researched without specifying whether it is day work, night work or both. The presence of night work is problematic, since it can influence the results found through its own effects on the biological clock and the circadian rhythm.

However, despite these difficulties, given their increasingly widespread practice, there is a growing body of scientific work on them. The cardiovascular effects now seem to be well established. These schedules also seem to be the cause of psychological disorders, such as depression, anxiety, sleep problems, sleepiness or addictions. And more specifically, they could be related to the onset of chronic pain of the locomotive system or gynaecological effects.

The question therefore arises of whether there is a specific risk linked to this overload of working hours, which must be considered because such risk could be cumulative with other occupational risks. Hence, it is necessary to continue researching on these long hours and their impact on health, though better characterising them to highlight their specific effects regardless of any other hourly exposure, night work in particular.

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