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Working time concerns the hours of the day and the days of the week that work takes place. Most people have standard working hours between 0800 and 1800 on week days. But work also takes place at non-standard hours in the evening, at night and on weekends. Non-standard working times constitute an important part of the economy and society. Work at non-standard hours may have negative effects on the health and well-being of workers because of tiredness and problems of combining work and private life.

Distribution of non-standard working times in Europe

Working time is well documented in labour statistics. Mostly the number of working hours and the percentage of part-time contracts is documented. The incidence of non-standard working hours in the European Union (EU) is studied every five years by means of the European Working Conditions Survey (EWCS)[1]. An important finding in this survey is that the average length of the European working week is decreasing, which is partially related to part-time work being more popular.

According to the EWCS 2010 nearly 24% of all workers work part time, which is defined as working 34 hours or less. On average 38% of all women work part time, compared to 13% of men. There is a considerable variation in part-time work between European countries. In the Netherlands more than half of all workers work part time, followed by Belgium, Denmark, Ireland and the United Kingdom (UK) where about 30% of workers work part time. Women often work part time to combine work and family care[2].

In the past 20 years the length of the average working week in the EU-12 (number refers to the number of member states during the first survey year, for an overview of the EU members and other countries in the EWCS sample, see table 1) has fallen from 40.5 hours in 1991 to 36.4 hours in 2010 (37.5 hours in the EU-27 in 2010). Another important fact from this survey is that the standard five-day working week (40 hours between 0800 and 1800 from Monday to Friday) is still the norm for most Europeans workers. 

Table 1: Overview of member states of the EU belonging to the EU-12, EU-15, and EU-27*, and other countries in the EWCS sample of 2010



Night and shift work

In the EWCS night work is defined as work between 0000 and 0600. Shift work may imply night work (night shifts), but also involves shifts in the morning, afternoon, evening, and/or weekend. In figure 1 the incidence of night work is given, because this is the part of shift work with the highest impact on health. There is no clear geographical pattern in the distribution of night work.


Night work tends to decline in Europe. In 1995 the EWCS indicated that 20.6% of all workers in the EU-15 worked at least one night per month. In 2010 this declined to 17.2%. In the EU-27 this percentage dropped from 18.7% in 2000 to 17.9% in 2010. Workers of all ages may work at night, but men, self-employed, and workers in the service sector do so more often than others.

Long working hours

The term ‘long working hours’ may refer to working days that are longer than eight hours and working weeks that are longer than 40 hours, but also to working days longer than 10 or 12 hours or working weeks longer than 48 hours. In section 2.2 it will be outlined that, in particular in Anglo-Saxon and east Asiatic countries, long working days of 12 and more hours occur. In Europe long working hours are often related to overtime and extended working hours in the case of compressed working weeks[3].

On average about 24% of European workers (EU-27) had a working week that lasted more than 40 hours in 2010 (figure 2). The incidence of long working hours is highest in a number of south-eastern European countries and Turkey.


In 2000 29% of the workers in the EU-27 had a working week that lasted more than 40 hours. The incidence of long working hours is gradually declining in most countries. Men, self-employed, and industrial and high-skilled workers more often have working weeks that exceed 40 hours. Young workers (less than age 30) often have shorter working weeks.

Weekend work

Weekend work implies working Saturdays and Sundays. Weekend work has tended to decrease slightly in Europe. In 2000 about 56% of the working population in the EU-27 worked at least one day per month in a weekend. In 2010 this was 53% (figure 3). Males, young people, and self-employed work more often at weekends and weekend work is more often found in service-oriented sectors.


Figure 3 illustrates that, in in 2010 in all 34 European countries covered by the EWCS survey, weekend work constitutes an important part of economic activity, but there is a greater occurrence in most south-eastern countries and Turkey.

Work and private life

Work at non-standard hours may cause problems with regards to reconciling work and family life. Figure 4 indicates that, on average, 18.5% of European workers reported difficulties in achieving a satisfactory work–life balance in 2010. In 2000 this was 19.6% and in 2005 this was 20.5%. Combining work and private life is less often a problem in north and west European countries.


Males, workers aged 30 to 50, and self-employed more often have problems in fitting working hours with hours for family life or social commitments outside work.

Effects of non-standard working times on health and well-being

There have always been workers who needed to work at night and at times when most people are free. But in the industrial revolution the invention of the steam engine and the light bulb made it possible to organise massive amounts of workers to work during all 24 hours of the day and seven days of the week. From that time the negative effects of, in particular, night work and long working hours became visible. Nowadays a huge body of research confirms these effects. Only some of these studies can be summarized here.

Night and shift work

The negative effect of night work on health is related to the biological clock of human beings, which are set to day activity. Working at night is more exhaustive than working in the daytime. Body functions become less active due to hormonal secretion[4]. Additionally, sleeping in the daytime is less restorative because body functions are set to optimal activity. Most people will not experience serious negative effects after one night of work, but with a higher number of night shifts in succession problems emerge such as: fatigue[5], mistakes and accidents[6], and also due to reduced lighting (physical agents; lighting), decreased productivity[7], and emotional exhaustion and job stress[8]. Also the immune system becomes less effective so that people are more vulnerable to health problems health and well-being and exposure to dangerous substances[9] and: risk management tools for dangerous substances. In the long run cancer is related to night work, in particular breast cancer[10]. Night work may also have negative effects on sleep duration, smoking, no exercise and obesity[11], and on eating habits[9], leading to gastrointestinal and nutritional problems[12]. In working time legislation the number of consecutive night shifts is often restricted. Knauth and Hornberger[13] reviewed working time literature and proposed a maximum of three consecutive night shifts.

Long working hours

In the literature the negative health impact of long working hours is most often confirmed when working days last 10 hours or more and working weeks last 48 hours or more[14][15]. Long working hours more often are a problem in Anglo-Saxon and eastern-Asiatic countries[16][17][18] than in European countries, including the Anglo-Saxon countries. For instance, in Canada, New Zealand, Australia and the United States the average number of working hours per year lies between 1,800 and 1,900; in Thailand, Hong Kong and South Korea it lies between 2,250 hours and 2,500 hours per year; and in Europe it lies below 1,700 hours per year[17].

In Europe long working hours are related to working overtime (and not in the standard employment contract), the compressed working week, and the self-chosen working times of the self-employed[19]. Long working hours are related to increased tiredness[3][16], but also aggravate the effects of exposition to burdening working circumstances. Exposition to physically burdening work, for instance, may lead more rapidly to musculoskeletal problems in case of long working hours[20]. The type of work therefore is an influencing factor. Non-exhaustive work and task variation are considered more appropriate for long working days than exhaustive and repetitive work[20]. An opposite problem is that, due to long working hours, the number of hours for sleep decreases, which may also lead to health problems because of sleep loss[11][14]. Long working hours may lead to all kinds of sleep loss and fatigue-related problems, such as accidents[6], health problems[14], and coronary heart disease[21]. Another effect is that long working hours interfere with health-related lifestyle factors, with negative effects on smoking behaviour, no exercise and obesity[11]. In the past century, periods of war in particular caused extremely long working hours. After World War I and II research confirmed the negative effects of long working hours on the production capacity of workers[22][23][24][25]. War products manufactured at the end of extremely long working days often failed to function correctly.

Weekend work

Weekend work refers to work on Saturdays and Sundays. Night work and long working hours can also take place during the weekends but have the same effect as working on weekdays (see 2.1 and 2.2). Weekend work in the daytime in general has the same effect on health as daytime work during weekdays. What is different is that weekend work has social implications related to family life and other social activities. This is discussed in 2.4.

Work and private life

Work at non-standard times may cause stress and emotional problems[8]. This study shows that employees with weekend work reported more emotional exhaustion, job stress and psychosomatic health problems than employees not involved with weekend work. Employees on non-standard work shifts reported significantly higher overall burnout, emotional exhaustion, job stress and health problems than employees with day work.

These problems may also emerge from the tension of not being able to combine work and private life, or may continue in private life. Presser[26] found that working in the evening, at night, in the weekend, and/or with rotating schedules affects the likelihood of marriages ending in separation or divorce within approximately five years. Nabe-Nielsen and colleagues[27] found that a misfit between working time preferences and actual work at non-standard times was associated with an increased dissatisfaction with working hours and/or an increased intention to leave the workplace because of one's working hours. Non-standard working hours can be in particular disruptive for work–life balance when employees are in a precarious employment situation with causal or temporary work, while regular and predictable non-standard working hours and non-extended working hours can contribute to a better work–life balance[3].

Individual differences and individual choices

Individual choices of employees are often related to career decisions and decisions related to the combination of work and private life. Having a health care job, for instance, often also implies working at night and at the weekend. Family care may be an important factor for working at non-standard times, in particular when the partner has a standard day job and takes over care responsibilities.

Individual differences related to non-standard working times often have weak correlations in research. One reason for the reduced visibility of individual differences is that people differ strongly in physical constitution and health status which leads to health selection on the labour market. This means that people who dislike or are not able to work during non-standard hours or with long working hours are not likely to apply for these jobs. On the other hand, people tend to leave the job when problems related to non-standard working times or long working hours emerge. Only people with good physical condition and strong motivation are able keep their job with non-standard working times for a long time (healthy worker effect). This is for instance visible in the literature in the often good health conditions of older shift work groups. Young age is often considered to be related to better shift work tolerance[28].

Overview of intervention techniques

Optimal intervention techniques may prevent negative effects of non-standard working times. Four ways of influencing the negative effects of working time are distinguished.

The role of governments and social partners

Governments regulate working time by law. In Europe this is regulated by the EU’s Working Time Directive (2003/88/EC)[29] or some other sectoral regulations. Under the EU’s Working Time Directive, each member state must ensure that every worker is entitled to:

  • a limit to weekly working time, which must not exceed 48 hours on average, including any overtime.
  • a minimum daily rest period of 11 consecutive hours in every 24.
  • a rest break during working time, if the worker is on duty for longer than six hours.
  • a minimum weekly rest period of 24 uninterrupted hours for each seven-day period, which is added to the 11 hours of daily rest.
  • paid annual leave of at least four weeks per year.
  • extra protection in the case of night work (for example, average working hours must not exceed eight hours per 24-hour period; night workers must not perform heavy or dangerous work for longer than eight hours in any 24-hour period; there should be a right to free health assessments and in certain situations, to transfer to day work).

In the 20th century social partners achieved an important role in the negotiation on working time and financial compensation by social agreements OSH in general. Nowadays working time is an important term of employment, directly after salary OSH Management and organisation. In these social negotiations interests may be balanced to prevent negative effects. Trade unions may negotiate better OSH situations and may convince employers to abandon too much night work and overtime, because increased tiredness lowers the production capacity of employees. The salary of employees is increased when working non-regular hours and overtime, but they suffer more because of increased tiredness and a negative work–life balance. Trade unions may be able to prevent too much irregularity and prevent sickness and disability in the long run.


Rosters are important tools to regulate non-standard working times. Rostering is necessary when company production times exceed the workday of the employees or when the workflow is irregular. This mostly is the case when the company continues its activity in the evening, at night, and/or at the weekend. Rosters often involve a rotating sequence where employees alternately work in the morning, afternoon, evening, at night and/or at the weekend.

There is a huge amount of roster variants. An important distinction is regular versus irregular rosters. In regular rotating rosters the same number of employees is staffed during all hours. Regular rosters are mostly found in industry (for instance: chemical, metal and automotive companies) . Irregular rosters are applied when the staffing need varies over the day. They are applied, for instance, in health care facilities where most activity takes place during the day, and less staff is needed in the evening, at night and/or at the weekend.

Rosters can be constructed in such a way that they reduce the negative effects on health and work–life balance. Knauth and Hornberger[13] give an overview of roster rules from this point of view. Examples of these rules are that the maximum number of consecutive shifts has to be three, that forward rotation (first morning shifts, then evening shifts and then night shifts) is preferred to backward rotation, and that after a night shift there should be at least two days off. The maximum number of consecutive shifts should be 5–7. Bambra and colleagues[30] reviewed 26 shift work interventions and found that three factors are most effective considering health and work-life balance:

  1. switching from slow to fast rotation;
  2. changing from backward to forward rotation; and
  3. self-scheduling of shifts.

Self-scheduling or self-rostering

Most rosters are prearranged by social agreement[29], but worked out at the organisation level. This gives employees a chance to influence their personal roster by formulating roster preferences. Most companies comply to this and also to informal exchange of shifts among employees, as far as this does not interfere with the interests of the organisation. This practice was recently worked out one step further by allowing employees to ‘self-roster’. With self-rostering (also called self-scheduling, prioritised working hours or self-selected working hours), employees may select working hours which fit their personal needs and preferences.

Several studies have been carried out recently[15][27][31] that indicate that control over working hours is associated with improved well-being. But also a warning is given, because employees may not change their working hours or choose working hours which do not favour health. Software applications may be used for monitoring, so that shift-workers also improve their health and well-being by planning their own working hours.

Technical and organisational solutions

As an alternative to making use of flexible working hours, companies can also consider a number of other organisational measures to meet the fluctuations in production demand (work organisation; Job design; WEI-11-15-5). Examples are: flexible staffing of internal personnel over different work places or functions, hiring external personnel, ‘flexible working hours’ by giving workers the possibility to decide about the exact time of starting and finishing work, applying logistic solutions such as stockpiling, and reconsidering the production process. However, in a number of cases this is not possible, because production processes require continuous operation or technical investment is too high.

Also, temporary alleviating solutions to improve personnel functioning are possible. Pallessen and colleagues[32] reviewed a number of countermeasures to reduce the negative effects of night work. They found research supporting the positive effects of applying bright light therapy, melatonin administration, naps (small periods of sleep during working time), use of stimulants to improve wakefulness, use of hypnotics to improve daytime sleep, and proper work scheduling. But it is unknown if these effects have long-term consequences. Insufficient studies were found that confirm the effects of proper personnel selection, exercise, and sleepiness-detection devices. 

Future developments

The development of working time is related to many social, political, legal, and economic aspects. Prediction based on trend analysis is almost impossible. From 1995 to 2010 the incidence of night work, long working hours, weekend work and work–life imbalance has been decreasing in the EU. But that does not mean that these trends continue or that the negative effects are also decreasing. Currently several initiatives are taking place that may influence the development of working time in Europe. Only some are described.

The European Agency for Safety and Health at Work issued a report in 2007 on new and emerging psychosocial risks related to occupational safety and health[3]. Irregular and flexible working time is seen as an important new risk. Employers stress the necessity for more flexibility in working hours to cope with competition. This includes in particular the demand for more flexibility in labour contracts, non-permanent employment, unpredictable working hours, part-time work and irregular working hours. But when the employees are unable to choose their working hours, this may lead to health problems[3].

In the European Union the Lisbon Treaty of the European Union of 2009 states that every worker has the right to limitations of maximum working hours, to daily and weekly rest periods and to an annual period of paid leave.To protect workers against too much deregulation of working time and the wish of employers for more flexibility, the Conditions of Work and Employment Programme (TRAVAIL) of the International Labour Organization (ILO) has identified five significant dimensions of decent working time[33]. The dimensions are:

  • working time arrangements should promote health and safety;
  • be ‘family-friendly’;
  • promote gender equality;
  • advance the productivity and competitiveness of enterprises; and
  • facilitate worker choice and influence over their hours of work.


[1] Eurofound – European Foundation for the Improvement of Living and Working Conditions, European Working Conditions Survey 2010, Survey mapping tool. Retrieved 5 December 2012, from:

[2] Eurofound – European Foundation for the Improvement of Living and Working Conditions, European Working Conditions Survey 2010, Survey mapping tool. Retrieved 5 December 2012, from:

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[8] Jamal, M., ‘Burnout, stress and health of employees on non-standard work schedules: a study of Canadian workers’, Stress and Health, Vol. 20, No 3, 2004, pp. 113-119.

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[22] Kossoris, M.D., Kohler, R.F., Hours of work and output, US Government Printing Office, Washington DC, 1947.

[23] Muscio, B., Lectures in industrial psychology, G. Routledge & Sons, London, 1920.

[24] Sargant Florence, P., Economics of fatigue and unrest and the efficiency of labour in English and American industry, Allen & Unwin, London, 1924.

[25] Vernon, H.M., Industrial fatigue and efficiency, Routledge, London, 1921.

[26] Presser, H.B., ‘Nonstandard work schedules and marital instability’, Journal of Marriage and Family, Vol. 62, No 1, 2000, pp. 93-110.

[27] Nabe-Nielsen, K., Kecklund, G., Ingre, M., Skotte, J., Diderichsen, F. & Gardea, A.H., ‘The importance of individual preferences when evaluating the associations between working hours and indicators of health and well-being’, Applied Ergonomics, Vol. 41, No 6, 2010, pp. 779-786.

[28] Saksvik, I.B., Bjorvatn, B., Hetland, H., Sandal, G.M. & Palessen, S., ’Individual differences in tolerance to shift work – A systematic review’, Sleep medicine reviews, Vol. 15, No 4, 2011, pp. 221-235.

[29] European Commission. Employment, Social Affairs & Inclusion, Working Conditions. Retrieved 5 December 2012,, from:

[30] Bambra, C.L., Whitehead, M.M., Sowden, A.J., Akers, J. & Petticrew, M.P., Shifting Schedules. ‘The health effects of reorganizing shift work’, Am J Prev Med, Vol. 34, No 5, 2008, pp. 427-434.

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[32] Pallessen, S., Bjorvatn, B., MagerØy, N., Saksvik, I.B., Waage, S. & Moen, B.E., ‘Measures to counteract the negative effects of night work’, Scand J Work Environ Health, Vol. 36, No 2, 2010, pp. 109-120.

[33] Boulin, J-Y., Lallement, M., Messenger, J. & Michon, F. (eds.), Decent working time: new trends, new issues, ILO, Geneva, 2006. Retrieved 5 December 2012, from:

Further reading

Only home pages are given because these sites contain information on working time on numerous pages:

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Klaus Kuhl

Irene Houtman


Richard Graveling