Finland: Longer, fast-rotating shifts better for employee health

A new study by the Finnish Institute of Occupational Health shows that the harmful effects of shift work can be alleviated by using fast-rotating 12-hour shifts instead of 8-hour shifts. Industrial employees working 12-hour shifts reported greater job satisfaction, more alertness and better sleep, health and performance at work.

About the study

A study by the Finnish Institute of Occupational Health (FIOH) has explored the effects of different types of shift work systems on employees’ health and well-being. It compared three systems of shift work, all of which operate on a forward-rotating basis.

Table 1: Comparison of three types of shift-work systems
12-hour shifts (fast) 8-hour shifts (fast) 8-hour shifts (slow)
  1. Two 12-hour morning shifts
  2. Two 12-hour night shifts
  3. Six days off
  1. Two 8-hour morning shifts
  2. Two 8-hour evening shifts
  3. Two 8-hour night shifts
  4. Four days off
  1. Four 8-hour morning shifts, one day off
  2. Four 8-hour evening shifts, one day off
  3. Four 8-hour night shifts
  4. Six days off






Firstly, correlations were investigated between the shift systems and employees’ sleep, health, well-being at work, occupational safety and sickness absence. A second objective was to identify practices and models that improve employee well-being in 12-hour systems.

The research was carried out by a group of seven researchers at FIOH. It was initiated after some companies in the industry sector requested information on best practice for 12-hour shift systems and their effects on employees’ well-being and occupational safety. Partly funded by the cooperating companies, the study is part of the Working hours, health, well-being and participation into working life programme, coordinated by FIOH.

Background information

Shift work is widely known to have adverse health effects: correlations have been found with incidence of cancer, diabetes, cardiovascular disease and lowered fertility, as well as sleeping problems, fatigue and stress, which can lead to accidents at work. When someone is working shifts, their social life also often suffers, because of the irregular and unsocial hours they work. Previous research has shown that 8-hour shift systems with fast rotations better enable employees to recover than slowly rotating 8-hour systems. Studies on 12-hour shift systems with slow rotations have also suggested that risks related to fatigue tend to accumulate in such circumstances, although employee satisfaction is often high. However, there have been fewer studies on 12-hour systems with fast rotations.


The study encompassed nine production units at three big paper and chemical businesses operating in Finland: Metsä Group, Neste and BillerudKorsnäs. Comparisons were made between units using different shift work systems, and longitudinally within units shifting from 8-hour systems to fast 12-hour systems. The data utilised included survey responses, registry data and interviews.

The surveys investigated various aspects of employee health and well-being. They involved 599 responses (91% male) across the nine units in the spring of 2014, and 476 follow-up responses one year later. Thematic interviews were conducted in 2014–2015 with eight employer representatives and 10 employee representatives from the four units that had switched from 8-hour to 12-hour systems. The interviews were used to collect information on and experiences of the implementation of the 12-hour system implementation, with a focus on the implications – in terms of well-being, safety and best practice – of shifting from one system to another. Finally, registry data covered employee sickness absences and injuries from 2008 to 2015.

Key findings

Employee experience

It was found that 12-hour shifts, on average, were better for job satisfaction and for employees’ experience of alertness, sleep quality, health and work performance. The survey results showed that 98% of the employees working in a 12-hour system were satisfied with their shift system, compared with 75% of those in fast 8-hour systems and 65% in slow 8-hour systems. Those working 12-hour systems slept longer and better, felt more alert and recovered better from work. They also reported better work ability and fewer problems with shift-related health and well-being at work. The observed differences between systems were significant both in the inter-unit comparison and in the longitudinal intra-unit comparison, where one unit switched from an 8-hour system to a 12-hour system.

Employer perspective

Employers also found 12-hour shifts preferable to 8-hour shifts. Managing production-related problems was found to be easier, and it was felt that risks in terms of safety and spoilage were potentially smaller. The flow of information grew more efficient as employee changes were reduced: in a 12-hour system, one employee or team could usually carry out a task from start to finish, without workers in the next shift having to take over. However, communications and reporting in a 12-hour system had to be enhanced, as an employee would need more updating after the six-day leave period between night and morning shifts than after the shorter leave periods of 8-hour systems. This was found to add to the managerial workload. Both employees and managers said that, in order to facilitate long 12-hour shifts, rotating between different tasks would be beneficial. Such arrangements would require smooth information flows, a diversifying of employee skills and know-how, and employees' committing to well-functioning backup systems.

Sickness absence

Registry statistics on sickness and injury-related absences did not significantly differ between shift systems. The annual occurrence of sickness absence, as well as the average number of sickness days, was slightly lower in the 12-hour system than in the 8-hour systems; possible causality and underlying mechanisms for this finding, however, need to be further explored. There were also few significant differences in the occurrence of accidents or near-accidents at work or during a commute to work. Near-accidents were reported most frequently in slowly rotating 8-hour systems, but the frequency of such incidents was too low for conclusions to be drawn about any relationship between them and specific shift systems.

Recommendations from FIOH

Based on the results, FIOH recommend the use of fast-rotating 12-hour systems; in particular, these are preferable to slow 8-hour systems. The findings show that the 12-hour fast-rotation system significantly improves job satisfaction, employee alertness, well-being at work and work ability. Recommended hours for shift changes are 07:00 and 19:00. A minimum of six months should be allowed for a smooth transition from one system to another. The recommendations apply to male-dominated workplaces in the industry sector, but not in a general way to physically demanding work, challenging work environments or female-dominated sectors. FIOH also points out that 12-hour systems do not solve the problem of night-shift fatigue, and recommends physical activity and light meals during night shifts in all shift systems.


In Finland, 23% of salaried employees worked some form of shift system in 2014. Industrial work usually follows regularly rotating 8- or 12-hour shift systems; increasingly, fast rotation systems are being used. In the rest of Europe, 12-hour shift systems are becoming more common but they generally rotate more slowly, with more 12-hour working days in a row before a longer period of rest. As noted above, the study suggests that slow-rotating 12-hour shift systems may increase risks related to fatigue.

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