In brief
In shift work, fatigue is not only the employee's problem but a source of hazard that must be included in the risk assessment. The direction and speed of rotation, the number of consecutive nights and the tasks placed in the last hours of the night shift directly affect the likelihood of accidents and errors. Forward rotation (morning → evening → night), not leaving critical tasks to the end of the night and monitoring fatigue indicators by hour are three basic, practical measures.
Why is fatigue in shift work an OHS risk?
The human body runs on an internal clock of roughly 24 hours: sleep, body temperature, attention and reaction time follow a regular wave during the day. Someone working at night works against this wave, and during the day often cannot sleep enough because of light, noise and family life. The result is a sleep debt that builds up over days. That is why shift work increases fatigue risk: a tired employee notices later, reacts more slowly and skips routine steps.
The legislation addresses this topic not with a separate "fatigue regulation" but with general principles. Art. 5 of Law No. 6331 requires the employer, when choosing work organisation, to prevent in particular the adverse effects of monotonous work and work pace on health and safety; Art. 10 requires all hazards to be included in the risk assessment. The shift pattern is a work organisation decision and has a place in the risk assessment. For how to measure the psychosocial dimension of fatigue, see our article on psychosocial risk factors.
Shift rotation: direction and speed
Shift rotation describes how employees rotate between shifts. Two variables matter: direction (from which shift to which) and speed (how many days or weeks are spent on the same shift).
In Türkiye, there is a legal framework for this choice. Under Art. 69 of Labour Law No. 4857, night work may not exceed 7.5 hours. Under the regulation on shift work, employees on the night shift are worked at night for at most one working week and are moved to the day shift the following week; a two-week rotation can also be applied. An employee whose shift changes cannot be put to work on the other shift without at least 11 hours of uninterrupted rest. For details of these rules, see our article on night work and the 7.5-hour rule. Within this framework, the choice of direction and speed is left to the employer.
| Pattern | Example | Strength | Point to watch |
|---|---|---|---|
| Forward rotating, weekly | 1 week mornings, 1 week evenings, 1 week nights | Longer rest at changeovers; suits the direction in which the internal clock adapts | Sleep debt builds up towards the end of the night week |
| Backward rotating, weekly | Morning → night → evening | Practically none | Rest is shortened on changeover days; the 11-hour rule is easily breached |
| Two-week rotation | 2 weeks nights, 2 weeks days | Less frequent changes | More consecutive nights; more sleep debt builds up |
| Fast, forward rotating | 2 mornings, 2 evenings, 2 nights, then rest | Few consecutive nights | Frequent changes; needs to be trialled with employees and the workplace physician |
Why is forward rotation preferred?
Forward rotation means shifts moving clockwise: morning → evening → night. The human internal clock adapts more easily to moving sleep time later than to bringing it earlier; everyone knows that going to bed late one night is easier than getting up very early one morning. Forward rotation runs in the same direction as this tendency.
The second advantage is rest time. Consider a three-shift pattern of 08–16, 16–24 and 24–08:
- Forward changeover: An employee who finishes the night shift (24–08) moves to the morning shift (08–16) in the next period. They rest for 24 hours until the following morning.
- Backward changeover: If an employee who finishes the night shift at 08.00 is rostered for the evening shift (16–24) on the same day, only 8 hours remain in between. This both breaches the 11-hour rule and sends the employee into an evening shift without sleep.
Give the person who prepares the shift rota a simple check: at each changeover, how many hours are there between the end of one shift and the start of the next? Any changeover under 11 hours is a legal problem, and any changeover close to 11 hours is a warning in terms of fatigue.
How are critical tasks planned at the end of the night?
Attention and reaction time weaken in the hours after midnight and towards morning, which coincide with the lowest point of the internal clock. The last hours of the night shift, combined with the fatigue of several consecutive nights, are the worst time for a critical task. So the planning rule is clear: do not leave high-risk tasks that require attention to the end of the night shift.
Tasks to consider in this context are:
- Maintenance and breakdown work requiring energy isolation,
- Die changes and setting on presses and injection moulding machines,
- Transfer and filling of hazardous chemicals,
- Permit-controlled work such as confined space entry and hot work,
- Heavy forklift traffic at the loading dock,
- Final checks that are critical for quality.
If it is unavoidable, take compensating measures: do the task with two people and cross-checking, tie the steps to a checklist, give a short break before the task and make sure the lighting is sufficient. Adding overtime at the end of the night shift moves fatigue into the riskiest hours; remember also that the night shift cannot exceed 7.5 hours.
Shift work sleep problems and advice for employees
Shift work sleep problems start with daytime sleep after the night shift being short and broken. Include the following practical advice in the information given to employees:
- Darken the room for daytime sleep and keep it quiet; share your sleep times with your family.
- Try to sleep at the same time every day; keep your sleep time fixed during the night week.
- Have caffeinated drinks in the first half of the shift; stop towards the end of the shift.
- Prefer light, regular meals over heavy meals during the night.
- Talk about fatigue risk for employees who will drive after the night shift; if possible, arrange a shuttle or shared transport.
In the health surveillance of night workers, the workplace physician assesses sleep patterns, sleep problems and health conditions that make night work difficult. Decisions such as moving an employee whose health has deteriorated because of night work to the day shift are made on the basis of the physician's assessment. In our workplace physician service, we plan the examination programme for shift workers with these topics in mind.
Fatigue risk management: monitoring the signs
Fatigue risk management is not about blaming individuals but about finding the points in the system that produce fatigue. To do this, monitor both individual signs and patterns in the records.
Signs that supervisors and co-workers can notice on site: repeated yawning, eyes closing, slower reactions, forgetting simple steps, repeating the same mistake, sudden irritability and absent-mindedness in conversation. Set up a system in which the person who notices these signs can say so without hesitation; an employee who reports their fatigue must not be penalised.
| Indicator | Where is it taken from? | What does it tell you? |
|---|---|---|
| Near miss and accident records, by hour | Near miss reporting system, accident records | Clustering at certain hours, end-of-night effect |
| Errors, scrap and quality deviations, by shift | Production and quality records | Increased loss of attention on the night shift |
| Overtime and number of consecutive days worked | Timesheets | Employees approaching legal limits and building up sleep debt |
| Number of consecutive nights | Shift rota | Fatigue load of the rotation pattern |
| Use of sick leave and leave | Human resources records | Health problems linked to the shift pattern |
Collecting near miss records with the time of day is the basis of this table; for how to set this up, see our article on the near miss reporting system.
Practice in the automotive supplier industry
Automotive supplier businesses working in shifts in Bursa's OIZs (organised industrial zones) plan their production according to the carmakers' schedules. When demand rises, the first solution that comes to mind is overtime and weekend work; fatigue risk also builds up most in these periods. A practical start could be:
- Check the current shift rota for direction and changeover rest; correct backward changeovers.
- Move die changes and planned maintenance to the first half of the night shift or to the day.
- Add time and shift information to near miss records and review them by shift every three months.
- Write shift work and fatigue into the risk assessment as a separate heading.
For how to distribute OHS specialist and physician visits in shift-based production, see our article on OHS in shift-based production in Bursa's OIZs. You can use our risk assessment service to incorporate your shift pattern into the risk assessment, and the OHS calendar tool to track renewal dates.
Frequently Asked Questions
What does forward-rotating shift mean?
It is a rotation in which shifts move in the direction morning → evening → night. This direction is in line with the tendency of the human internal clock to shift sleep time later, and provides longer rest at changeovers.
How many consecutive weeks can the night shift last?
Under the regulation on shift work, employees on the night shift are worked at night for at most one working week and moved to the day shift the following week. The regulation also permits a two-week rotation; in terms of fatigue, it is better to keep the number of consecutive nights low.
Should fatigue be written into the risk assessment?
Yes. Law No. 6331 requires the health effects of work organisation and work pace to be prevented; the shift pattern is also a work organisation decision. In shift-based workplaces, fatigue should be addressed as a separate heading in the risk assessment.
Should maintenance not be done at the end of the night shift?
Not unless it is unavoidable. Attention is at its lowest towards morning; move work such as maintenance requiring energy isolation and die changes to the first half of the shift or to the day. If it is unavoidable, do the work with two people and a checklist.
A risk assessment that identifies and scores hazards on site, links each measure to an owner and a date, and has a clear renewal schedule.
Bursa SİSTEMER OSGB Technical Team — written from the field experience of our OHS specialists and workplace physicians. Legal information is valid as of the publication/update date; contact us for an assessment specific to your business.