GILBRETHX INSIGHTS · ISSUE 01 · NOVEMBER 2026
Why working-time compliance is only a starting point for understanding fatigue exposure in 24/7 operations.
By Eulália Gomes · Psychologist | Founder & Scientific and Strategic Lead, GILBRETHX
A schedule can look right on paper
In a hospital, a railway control room, a logistics hub or an industrial facility, operations continue while much of the world sleeps. People must be present, critical positions must be covered and the schedule must meet the applicable rules.
Once those requirements are satisfied, the roster may appear complete. Yet it leaves a different question unanswered: what does the arrangement of working hours mean for the people expected to remain alert, make decisions and perform safely?
The total number of hours matters. So do their timing, their sequence and the opportunities for recovery between duties.
Compliance is a foundation, not a fatigue assessment
Working-time protections are essential. The European Working Time Directive, for example, establishes a general entitlement to 11 consecutive hours of daily rest per 24-hour period, with defined derogations and sector-specific arrangements [1].
But rest time on a roster is not the same as sleep obtained. Travel, domestic responsibilities and the need to unwind all compete for that time. After night work, sleep may also have to occur during the biological day, when circadian rhythms and environmental conditions can make it more difficult.
The UK Health and Safety Executive states explicitly that compliance with working-time regulations alone is insufficient to manage fatigue risk [2]. That is not an argument against regulation. It is a reminder that a legal minimum and a comprehensive risk assessment answer different questions.
The same hours can create different conditions for recovery
Imagine two teams with identical monthly working hours, equivalent staffing coverage and schedules that comply with the rules applying to their work.
In one, duties follow relatively predictable sequences, and periods away from work are distributed consistently. In the other, night work and early starts are concentrated differently, long runs of duties occur more often and last-minute changes are common.
The hours are the same; the structure of exposure is not. This does not prove that workers on the second schedule are more fatigued. It does show why total hours and headcount alone are inadequate descriptions of the conditions created by a shift system.
A useful review examines night duties and early starts, shift sequences, intervals between duties, consecutive working days, overtime and the differences between planned and actual work. Each indicator describes part of the system; none is a direct measure of an individual’s fatigue.
What the science supports — and where it is cautious
A major review by Kecklund and Axelsson describes acute sleep loss associated particularly with night and early-morning work, alongside a wider body of evidence linking shift work to health and safety outcomes [3]. The mechanisms are plausible, but outcomes also depend on the individual, the task and the work environment.
Finland provides an instructive example of systematic working-time evaluation. The Working Time Traffic Light recommendations use objective records to examine characteristics of working hours. A 2026 review reported that regular use of the evaluation tool was associated with improved working-time patterns and fewer occupational accidents in the Finnish social and healthcare context [4]. These are observational associations, not proof that the same effects will occur in every organisation or sector.
Equally important is what remains uncertain. A 2023 Cochrane review found that evidence for many specific schedule adaptations improving sleep or sleepiness was limited or very uncertain [5]. There is no universal roster design guaranteed to be best for every workplace.
Use the data already available — and keep the limits visible
Many organisations already hold the information needed for a first structural assessment: planned rosters, actual hours, night duties, overtime, swaps, absences and staffing requirements. The starting point may be less about collecting new personal data and more about asking better questions of operational information.
Where do shorter recovery intervals cluster? How often does the real schedule depart from the planned one? Are demanding sequences concentrated in particular roles? Could an alternative preserve the required skills and coverage while offering more predictable or better-distributed recovery opportunities?
The answers can identify patterns worth examining. They cannot reveal how much any particular person slept, how sleepy that person feels or whether an error will occur. Schedule analysis is one component of fatigue risk management, not a substitute for understanding workload, individual circumstances, working conditions or employees’ experience.
Feasible improvements must be weighed against continuity, staffing, competence, fairness, costs and the applicable employment framework. Workers and operational managers need to be part of that assessment, and changes should be monitored rather than assumed to work.
A different question for operational leaders
When your organisation reviews a roster, what is discussed first: coverage, hours, cost, compliance? And where in that review do you systematically examine night-work exposure, demanding sequences and realistic opportunities for recovery?
A schedule is more than a timetable. It is a record of how an organisation distributes demands — and opportunities to recover — over time.
The important question is not only whether a schedule can be implemented. It is what that schedule asks of the people who must work it.
References & further reading
- European Parliament and Council. Directive 2003/88/EC, Article 3 and Chapter 5 (derogations). Source.
- UK Health and Safety Executive. Fatigue — human factors: key principles in fatigue management. Source.
- Kecklund G, Axelsson J. Health consequences of shift work and insufficient sleep. BMJ. 2016;355:i5210. Source.
- Härmä M, Karhula K, Turunen J, et al. Working time traffic light recommendations: development, use, and implementation in Finnish social and healthcare. Industrial Health. 2026;64(3):214–232. Source.
- Hulsegge G, Coenen P, Gascon GM, et al. Adapting shift work schedules for sleep quality, sleep duration, and sleepiness in shift workers. Cochrane Database Syst Rev. 2023;9:CD010639. Source.