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Guide: 8 Vs 12 hour shift patterns

The great debate…

Many and varied opinions are held around the eight Vs twelve hour shift pattern debate. These two most commonly worked shift pattern lengths bring with them a number of advantages and disadvantages depending on the scenario.
This guide looks at the eight Vs twelve hour shift pattern debate from an objective viewpoint, helping define the best solution for your shift working organisation and shift workers.
We consider best practice, the implications of Working Time Regulations and provide a sample rota with related calculations.
To summarise, we outline the steps required to successfully change shift patterns.

Longer Shift patterns – the Pros and Cons

Many factors come into play when deciding on a shift pattern, rota or roster.
The below list is not exhaustive, but touches on some key arguments behind the 8s versus 12s discussion:
  • Shift extension: Working Time Regulations stipulate a minimum 11-hour difference between shifts. Theoretically, shift extensions on a 12-hour shift pattern are limited to 13 hours – this is before any compensatory rest period is taken into account.
  • Missed shifts: If shifts are missed at short notice, the missed shift can be made up or ‘absorbed’ by extending an original 8 hour shift to 12 hours, extending the shift either side by 2 hours. This way, no replacement shift worker need be brought on site, as those already present provide the necessary cover. The reverse argument also applies: 8-hour shift patterns may incur back-to-backs (i.e. 16 hours total) and are not favourable.
  • Cover: Employees’ willingness to cover a colleague’s shift pattern is variable, particularly when it comes to night shifts. Volunteers to provide replacement cover for a 12-hour long night shift may be scarce – it can be much easier to find cover for an 8-hour shift, even at night.
  • White Space (time off between scheduled shifts at work): Extended ‘white space’ has repercussions in other areas. For example, longer spells between a shift worker being seen by a manager and greater consideration for re-connect time if a person has been inactive for a number of consecutive shifts. Lengthy shift patterns naturally accumulate more ‘white space’.
  • Flexibility: Once working to a 12-hour shift pattern, employees are generally reluctant to move back to 8-hour shifts; the pay-off is simply too compelling. As a consequence, future changes will be harder to negotiate.
  • Fatigue: Is the work physically or mentally demanding? What is the age profile of the workforce? There are a number of factors to be fully considered if shift pattern lengths are substantial and time between breaks limited.
There is also a flipside to each of the considerations above.
Below are some of the benefits of 12-hour shifts:
  • Days off: Number of weekends and days off are increased on a 12-hour shift pattern (note the figures in ‘Sample Rotas & Calculations’ section). There is also the potential to group days off and use ‘white’ space more effectively.
  • Work-life balance: Reduced total travel (time and costs) result in reduced stress levels, allowing shift workers more quality time with their families and facilitate a healthy work-life balance. 12-hour shifts typically run 0600-1800, 1800-0600 and thereby facilitate ‘quality’ family evening time. There is also greater opportunity for shift workers to attend to their personal issues (e.g. doctor and dentist appointments, child care).
  • Sickness: Because shift workers are more considerate of a colleague having to cover 12 rather than 8 hours, sick days are fewer. There is also proportionately more time off in a year for the sickness to fall into.
  • Focus: During a run of shifts, 12 hours between shifts leaves little time for distractions after travel to/from home, meals and sleep. Hence minds are more focused on the task in hand.
  • Consecutive days worked: Runs of shifts are shorter with longer shift patterns; consider typical runs of 3 or 4 shifts worked as 12 hours, versus say 5 shifts worked as 8 hours.
  • Handovers: Fewer handovers between shifts results in:
  • 1. Reduced downtime
  • 2. Reduced opportunities for miscommunication
  • 3. Reduced disruption to the rest of the workforce, with consequential  impact on productivity
  • 4. Reduced number of lock & tag changeovers where equipment isolations have been   necessary (e.g. maintenance, blockage clearance)
  • Increased productivity and ownership: Many shift workers spend the early part of their shift ‘getting up to speed’ / ‘settling things down’ / ‘tweaking & maximising’ – this is the ‘ramp’ period, which leads naturally into efficient working for the plateau (remainder of the shift). Assuming the ramp length is fixed, the plateau provides greater benefit for longer shift patterns. A longer shift pattern also provides more opportunity for job completion. Longer shift patterns therefore tend to instil a sense of accountability and completion.
  • Risk and regulation: Fatigue risk is often associated with long shift patterns. Yet simulated studies have shown levels of fatigue in 8-hour shift workers and 12-hour shift workers to be comparable, concluding there to be no great increase in fatigue caused by working longer shifts.

The Health & Safety Executive (HSE) has made observations in relation to the subject of fatigue. It notes that fatigue can induce poor performance through reduced alertness, reaction time, concentration, and poor decision-making. The HSE also points out that tiredness can cause errors, accidents and injuries.

Extra consideration is needed for night shifts, successive shifts, long shifts and inadequate breaks. There is no legislation relating specifically to shift work, however, under existing law, employers have a legal duty to manage the risks of shift work.
Fewer handovers between shifts results in compliance with:
  • Health and Safety at Work etc. Act 1974
  • Management of Health and Safety at Work Regulations 1999
  • Working Time Regulations 1998
  • Other industry specific legislation (e.g. Railway and Other Guided Transport Systems [Safety] Regulations 2006; The Air Navigation [No. 2] Order 1995; etc.)

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The extensive review of information concerning trends in risk relating to shift work has enabled an index to be created which is entirely measured on risk, as opposed to fatigue and performance. Though fatigue and risk indices are similar in many respects, in others, they diverge. The main differences are due to the effects of the time of day: the peak in risk occurs close to midnight, whereas the peak in fatigue tends to occur some five hours later, in the early morning. On this basis, a number of components can be drawn up to mitigate risk associated with shift work-related fatigue.
A cumulative component relates to the way in which individual duty periods or shifts are put together to form a complete schedule; the cumulative component associated with a particular shift depends on the pattern of work immediately preceding that shift.
A second component type is associated with duty timing, i.e. the effect of start time, shift length and the time of day throughout the shift.
Lastly, a job type / breaks component considers the content of the shift in terms of the nature of activity being undertaken and the provision of breaks during the shift.

Best practice   

The HSE prescribes no absolute right or wrong when it comes to shift pattern length. What should be emphasised is the need to fully consider shift patterns, rotas and rosters in relation to the work and the shift worker in a given shift working environment. Twelve-hour shifts can be more demanding than 8 hour shifts for the time that workers are on site.
On the other hand, people work considerably fewer shifts to achieve their total contracted hours. The HSE advises that night shifts are rotated (i.e. no permanent nights) and suggests the number of concurrent night shifts is kept low so that a worker’s body clock does not have time to adjust. Working fewer 12-hour night shifts in a pattern therefore has an advantage over working 50 per cent more 8-hour night shifts in a pattern.
Suggested best practice to mitigate risk: 
  • Plan an appropriate and varied workload.
  • Offer a choice of permanent or rotating shift patterns and try to avoid permanent night shifts.
  • Rotate shifts every 2-3 days or every 3-4 weeks, otherwise adopt forward rotating shift patterns.
  • Avoid early morning starts and try to fit shift times in with availability of public transport.
  • Limit shifts to 12 hours including overtime, or to 8 hours if the work is demanding, monotonous, dangerous and/or safety critical.


  • Encourage shift workers to take regular breaks and allow some choice as to when they are taken.
  • Consider vulnerable shift workers.
  • Limit consecutive working days to between 5 and 7 days and restrict long shifts, night shifts and early morning shifts to 2 or 3 consecutive shifts.
  • Allow 2 nights full sleep when switching from day to night shifts and vice versa.
  • Build regular free weekends into the shift schedule.


We have established that transferring from shorter to longer shift patterns (say 8 hours to 12 hours) directly results in fewer shifts being worked and an increase in the number of days off.
This can be enticing, but needs careful consideration of all the surrounding circumstances. There is no right or wrong.
We have also recognised that individuals’ attitudes to shift patterns, rotas and rosters will often be affected by factors such as age, marital status, parental status and other personal interests.
For some, 12 hour shift working will inhibit time spend on certain responsibilities / activities outside of work. For others, the opposite may be the case.
When considering changing shift patterns, it is good practice and beneficial to consult and involve shift workers in the process. Also consider the bigger picture, including the mental and physical demands of the work and aspects such as rest schedules.
Changes in the environment can sometimes make longer shift patterns more acceptable. Be equally aware of any additional support required (e.g. child care) to make a transition as smooth as possible and seasonal demands may also be a consideration. Initially, longer shift patterns can be introduced in a small area and the success of the change be evaluated. Evaluation should be based on health and safety reports, accident rates, absenteeism, levels of health and fatigue, production levels and other business methods, as well as on honest feedback from employees.
Learn from your findings and modify shift patterns, rotas and rosters in line with these learnings. Bear in mind that changing shift patterns can be iterative and continuously refined.

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Stephen Taylor, Head of Digital at Totalmobile, came on board in 2016 and brings over 20 years in digital marketing. Stephen is deeply versed in digital strategy and analytics. His SaaS and field service management expertise has made him a pivotal asset across Totalmobile sectors.