Laurence Weibel^[1]

1. Definition

Atypical working hours are any kind of working time that differs from “normal” working hours (working from Monday to Friday, from 7 a.m. to 8 p.m., with two successive days off): shift work, night work, evening work, weekend work, variable working hours, irregular working weeks, overtime, split working hours (breaks during the day).

Only night work is precisely defined in the French Labour Code, by Section L.3122-29, as ‘any work taking place between 9 p.m. and 6 a.m.’.

2. Characteristics of the exposure

Working atypical hours is not a marginal situation. In 2017, 44% of employees in France (i.e., 10.4 million people) had at least one atypical working day in the course of a month at their workplace, at home, or elsewhere. Saturday work is the most common non-standard working day, concerning 35% of employees, or 8.3 million people. Evening work comes second, with 23% of employees (5.5 million), followed by Sunday work, with 19% of employees (4.6 million). Finally, night work is the least frequent atypical working time, as it concerns 9% of employees (i.e., 2.2 million) (Létroublon and Daniel, 2018).

Atypical working hours are concentrated in certain occupations. Among the occupational groups with the largest number of employees working atypical hours are

• Nurses, midwives, care assistants, sales assistants, cashiers, cleaners, caregivers and domestic employees: all of them, occupations wherein women are predominant.
• Military personnel, police, firefighters, security guards, vehicle drivers, cooks, butchers and bakers: all of them, occupations wherein men are predominant.

Atypical working hours concern men slightly more than women (44.2% of men against 43% of women). Men work more often in the evening and at night, while women are more affected by Saturday work, but this is explained by a structural effect (age, profession, etc.) (Létroublon and Daniel, 2018).

3. Health effects

Night work has been widely studied and its effects on health are now well known (Anses, 2016). Other forms of atypical working hours, however, have been less studied. And when they are, the studies often mix them with night work. It is therefore difficult to assess the effects of these atypical but non-night working hours.

Based on a review of the literature, this article summarises the current knowledge of the effects on health and safety and on social and family life of these forms of non-standard working hours, excepting nights: split or split-shift work, evening work, Sunday work, on-call work, work with varied, unpredictable or flexible working hours, and pluriactivity.

3.1. In general terms

Workers doing atypical hours are more widely subject to multiple exposures, whether to certain products or toxins or to organisational constraints (Algava, 2014).

Employees exposed to atypical working hours also have a riskier lifestyle than those subject to standard working hours: smoking, alcohol consumption, less balanced eating habits. An increased prevalence of depressive symptoms, risk of obesity and sleep disorders is also highlighted (Winkler et al., 2018).

The social isolation associated with atypical working hours that are not compatible with private life is also linked to an increase in suicides (Chan Chee and du Roscoät, 2019). Indeed, atypical working hours make it more difficult to balance work and non-work life (Greubel et al., 2016).

There has even been noted an impact on the health (overweight) of workers’ children (Champion et al., 2012; Morissey et al., 2011). Time spent with children is affected by non-standard working hours, with a reduction in parent/child interactions (Hook et al., 2013).

3.2. The special case of on-call duty

The kind of work is characterised by the worker’s availability to answer the phone while at home or even to travel, if necessary.

The unpredictability of phone calls is a barrier to disconnection, as it maintains the mental workload and forces the worker to be on alert at all times (Paterson et al., 2016; Bamberg et al., 2012). This non-disconnection directly affects the quantity and quality of sleep (Hall et al., 2017) due to the stress and apprehension of being called (Ziebertz et al., 2017, Vincent et al., 2020).

The health effects of on-call duty are numerous: fatigue (Ziebertz et al., 2015), cognitive disorders (Lingenfelser et al., 1994), anxiety (Chambers and Belcher, 1994), mood disorders (Rankin et al., 1987), gastrointestinal functional disorders (Lim et al. 2017), sleep disorders associated with daytime sleepiness (Lindfors et al. 2006; Kaneita and Ohida 2011), headaches, visual fatigue, muscle pain, injuries, hearing problems in relation to sleep disorders and circadian alterations (Yang et al. 2015), dermatological effects and pain (Baek et al. 2018).

And, of course, disruption of social and family life (Heponiemi et al., 2014, Ziebertz et al., 2015) is associated with on-call duty.

3.3. The special case of Sunday work

Working on Sundays implies a loss of sociability with family and friends, as well as a reduction in leisure time, that goes beyond what can be observed on a weekday, due to the synchronising nature of this day (Boulin and Lesnard, 2016; Boulin and Lesnard, 2017). Moreover, this atypical work schedule is often part of weekly work rhythms that are themselves atypical (night work, staggered days in the morning or the afternoon, long weeks and short weeks) (ibid.; Létroublon, 2016).

Working on Sundays has an effect on perceived health, a highly predictive indicator of health status (Greubel et al., 2016). Working on Sundays is also associated with sleep disorders, probably because the ‘‘resting’ value of Sundays is different —due to the status of this day and the associated calmness— from that of other days of the week (Nachreiner, 2011).

Analyses from an American database show that Sunday is the day with the highest risk of accidents at work, with a 37% increase compared with other days of the week (Brogmus, 2007). These results are explained by the presence of more young people on Sundays, as well as fewer incumbents, less management, and the fact that working on Sundays sometimes constitutes a second job, thus increasing fatigue.

Moreover, in certain activities, particularly in hospitals, the reduced staffing levels at weekends have consequences on patient outcomes (increased mortality): it has even been called the ‘weekend effect’ (Pauls et al., 2017).

3.4. The special case of flexible, variable or unpredictable working hours

Flexible work can have benefits for employees when it allows for arrangements to best reconcile work and non-work life. In other words, flexibility is positive when employees have control over it (Berg et al., 2014; Lambert et al., 2008). Costa even suggests distinguishing between two forms of flexibility: he speaks of ‘variability’ when flexibility is managed by employers and ‘flexibility’ when the employee has broad control over his or her hours (Costa et al., 2006). In this view, it is not the variability that is harmful but the lack of control over the time system (Ibid.; Nijp et al., 2012).

Not surprisingly, the predictability of working hours is a variable with a particularly strong effect on women (Cornet, 2005).

For another part, flexible work is further associated with poor cardiovascular health, fatigue, and mental health effects (Costa et al., 2006, Arlinghaus et al., 2019). High schedule variability has recently been associated with emotional exhaustion in nurses (Dhaini et al., 2018).

In fact, the regularity and predictability of schedules and timetables are favoured by employees (Messing et al., 2014) because they allow for a better reconciliation between work and non-work life. The stability and predictability of schedules and work rhythms are important to enable workers to anticipate their planning and to have room for manoeuvre in organising their extra-occupational life (Costa et al., 2006, Kubo et al., 2013).

3.5. The special case of split shifts and evening work

‘Cut-off’ work refers to an atypical day structure with working time fragmented by breaks of varying length (usually over three hours) between two work periods.

Split working is not popular and is often suffered by a rather precarious population of workers.

A recent Swedish survey reports that split working, as well as unscheduled work and short rests (less than 11 hours), is cited by employees as one of the major problems of atypical working hours, well ahead of night work (Akerstedt and Kecklund, 2017).

Employees with split shifts work at times when many social and family activities take place, therefore becoming excluded from many of them.

One of the most well-documented health effects of split shifts is the sleep debt generated by these schedules (Short et al., 2016; Zhou et al., 2017). Working early in the morning or late in the evening interferes with the main sleep period and thus reduces sleep duration and, potentially, its quality. In addition, it is difficult to rest during break times, as employees often do not have time to go home.

Other health effects are documented for evening work. Working at this time is associated (Boisard et al., 2003; Greubel et al., 2016) with an increased risk of work-related injuries (Mustard et al., 2013)and also impacts eating habits, particularly by delaying dinner time. The frequency and circadian time of food intake have increasingly documented effects on health (Marinac et al., 2015; Varady 2016; Paoli et al., 2019). The time interval between dinner and bedtime appears to be a critical variable. Indeed, two recent studies have linked this time to breast and prostate cancer risks: the shorter the time between dinner and bedtime, the higher the risk (Kogevinas et al., 2018; Srour et al., 2018).

3.6. The special case of pluriactivity

Pluriactive workers are those who work for more than one employer or in more than one occupation. Women in low-skilled occupations are particularly affected by pluriactivity. They are often forced to work part-time, since pluriactivity rarely allows them to work full-time.

The primary risk of this type of work, common to all pluriactive workers (excluding part-time workers), is exposure to long working hours and, consequently, to sleep and daytime vigilance disorders (Marucci Wellman et al., 2016).

Pluriactive workers are also characterised by a higher accident rate. Stress (Lombardi et al., 2010), inexperience (Benavides et al., 2006), precipitous workload-related behaviour (Koukoulaki, 2010), and a lower management investment for non-full-time employees (Marucci-Wellman et al., 2014) are among the reasons cited.

Other health effects found in the literature include increased mortality (Cappuccio et al., 2010), diabetes (Gottlieb et al., 2005), hypertension (Gangwisch et al., 2006), cardiovascular diseases (Ayas et al., 2003) and body mass index (Lombardi et al., 2012).

Furthermore, the lack of schedule flexibility, which is also closely linked to the profile of pluriactive workers, results in lower job satisfaction (Bouwhuis et al., 2018).

Conclusions

Many of the effects of atypical working hours —excluding night work— on health, safety and social and family life are summarised in this chapter.

However, an analysis of the publications reveals that the characterisation of exposure is often imprecise: exposure to atypical working hours is often studied in individuals also engaged in night or shift work.

In this summary, only the studies in which the confounding factors linked to night work or shift work were sufficiently controlled are cited, hence the small number of publications. In future studies, a more detailed characterisation of exposure will allow a better understanding of the links between these atypical temporalities and the effects studied. The underlying physiopathological mechanisms are probably based on circadian alterations linked to altered meal times and exposure to light dependent on the atypical temporalities, on chronic stress mechanisms linked to psychosocial risk factors, and on mechanisms linked to sleep debt.

Additional epidemiological studies —with a more rigorous methodology— combined with experimental and mechanistic studies are therefore to be encouraged, in order to rapidly define prevention axes.

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