Summary
In short
- Hours rules count duty time. Fatigue is produced by sleep opportunity, circadian timing, time awake, workload and recovery, and only the first of those appears in a log.
- Consecutive nights, short turnarounds and the direction of shift rotation drive impairment more than weekly total hours.
- The hours that cause the incident are usually the ones nobody counted: commute, a second job, a call-out on a rest day, caring responsibilities.
- Circadian low points in the early hours produce impairment comparable in effect to significant alcohol levels, which is why safety-critical work scheduled then needs specific attention.
- Fatigue reporting must carry no penalty. Where reporting costs earnings or triggers a performance conversation, it stops and the hazard becomes invisible.
- Plot incidents by hour of shift and position in the roster cycle. The pattern is usually present in data organisations already hold and rarely examined.
What it is
What it is
What is a fatigue risk assessment?
An assessment of the factors producing impairment through insufficient or badly timed sleep: the schedule, the task, and the individual circumstances that the roster does not see. It concludes with controls and, where fitness is in question on the day, a decision about whether the person works.
Is compliance with hours of service enough?
No. Hours rules set an outer limit on duty time; they do not measure sleep obtained, circadian timing, workload during the shift, commute length or what the person did on their days off. Compliance with a maximum is a legal position, not an assessment of fitness.
When to use it
When to use it, and when not to
This assessment covers impairment from fatigue. Hours compliance is a separate record with a separate purpose.
Use it for
- Roster and shift pattern design, before implementation rather than after complaints
- Roles combining driving with loading, handling or customer interaction across a long duty period
- Night and early-morning work, and any safety-critical task scheduled in the circadian low
- Following an incident where fatigue is a credible contributing factor
- Where overtime, call-outs or staffing shortfalls have extended actual hours beyond the planned roster
Not for
- Hours of service records, which evidence legal compliance rather than assessing fitness
- Driver qualification files, which cover licensing and medical certification
- Medical fitness assessment, including screening for sleep disorders, which is a clinical activity
- Journey risk assessment, which addresses the route and conditions rather than the driver's state
- Disciplinary process, which must not share a record with fatigue reporting
Standards
What it is built against
Fatigue is regulated prescriptively in transport and through general duties elsewhere.
| Clause | Requirement | Where it lands |
|---|---|---|
| FMCSA 49 CFR Part 395 | Hours of service limits, mandatory rest and electronic logging for commercial drivers | Schedule factors |
| NSC Standard 9 (Canada) | Hours of service standard adopted provincially for commercial vehicle drivers | Schedule factors |
| ISO 39001 | Road traffic safety management system, including driver fitness among risk factors | Header |
| EU Directive 2003/88/EC | Working time limits, daily and weekly rest, and restrictions on night work | Schedule factors |
| ISO 45001 cl.6.1.2 | Hazard identification covering work organisation including shift patterns and workload | Task factors |
| HSE HSG256 | Managing shiftwork guidance, including roster design factors and fatigue risk assessment | Schedule factors |
| OSHA General Duty Clause | US route for recognised fatigue hazards outside regulated transport | Header |
| ISO 45001 cl.5.4 | Consultation with workers, who know which shifts and turnarounds are unmanageable | Individual factors |
What it does not cover
- Hours of service records, which evidence compliance with a legal maximum rather than fitness.
- Medical fitness assessment, including sleep disorder screening, which is clinical and confidential.
- Journey risk assessment, which covers route, conditions and vehicle rather than the driver's state.
- The driver qualification file, which holds licensing and medical certification.
- Performance management, which must be kept entirely separate from fatigue reporting.
Filling it in
Filling it in well
Three groups of factors, and the third is the one the organisation cannot see without asking.
Consecutive nights, turnaround length, shift duration, rotation direction, start times and predictability. These drive impairment more than weekly hours totals, and a compliant 48-hour week of consecutive nights with short turnarounds is more impairing than a longer week of days.
Commute at both ends, call-outs on rest days, shift swaps, overtime and, where disclosed, second jobs. You cannot mandate disclosure of everything, and you can build a roster with enough recovery that ordinary life does not push people into impairment, and ask about time awake at the point it matters.
Impairment in the early hours is well documented and comparable in effect to significant alcohol levels. Where lone driving, energy isolation, confined space entry or a critical check is scheduled then, the assessment should say so and the schedule should change where it can.
A fatigue report should result in redeployment away from safety-critical work for that shift and a look at what produced it. Where it costs earnings or triggers a performance conversation, reporting stops within weeks and the assessment is left working from a roster.
Audit findings
Common audit findings
Fatigue findings concentrate on the gap between planned and actual.
| Finding | Clause | What fixes it |
|---|---|---|
| Assessment built from the planned roster rather than actual hours worked. | ISO 45001 cl.6.1.2 | Capture actual duty including overtime, call-outs and swaps. |
| Hours compliance treated as evidence of fitness. | 49 CFR 395 | Compliance is a legal maximum; fitness is a separate assessment. |
| Consecutive nights and turnaround length not assessed. | HSG256 | These drive impairment more than weekly totals; assess them explicitly. |
| Safety-critical tasks scheduled in the circadian low with no additional control. | ISO 45001 cl.8.1 | Reschedule where possible, and add controls where not. |
| Commute time not considered in total time awake. | HSG256 | Include travel at both ends; long commutes convert a compliant shift into an impairing day. |
| Fatigue reports handled as performance matters. | ISO 45001 cl.5.4 | Separate the processes; penalising reports eliminates the data. |
| Incidents not analysed by hour of shift or roster position. | ISO 45001 cl.9.1 | Plot them; the pattern usually exists in data already held. |
| Staffing shortfalls producing sustained overtime with no reassessment. | ISO 45001 cl.6.1.2 | Treat sustained overtime as a change requiring review, not as a temporary condition. |
| Roster changed without assessing the fatigue implications first. | HSG256 | Assess before implementation; consultation at design is cheaper than complaints after. |
| No route for someone to declare unfit on the day. | ISO 45001 cl.7.3 | Provide it and honour it; the alternative is people driving impaired rather than saying so. |
Worked case
Case in point: the compliant driver
A driver finished a delivery run at 4pm, drove seventy minutes home, and was called out at 11pm to cover an urgent collection after another driver called in sick. He had been awake since 5am. The electronic log showed him well within his available hours: he had taken his required rest, his duty time was inside the limit, and every regulatory measure was satisfied.
By the time he reached the motorway he had been awake for eighteen hours, in the circadian low, at the end of a full working day, with a commute at each end that appears in no log anywhere.
Nothing happened on that occasion. The point is that no system anywhere in the operation could have detected the exposure, because every system measured duty time and none measured time awake.
Definitions
Definitions and key terms
- Circadian low
- The period of lowest alertness, typically between about 2am and 6am, when impairment is greatest independent of hours worked.
- Turnaround
- The interval between finishing one shift and starting the next, which determines sleep opportunity more than shift length does.
- Time awake
- Hours since waking, a stronger predictor of impairment than duty hours and absent from hours of service records.
- Rotation direction
- Whether shifts move forward or backward through the day. Forward rotation is generally better tolerated.
- Sleep opportunity
- The realistic window available for sleep once commute, meals and personal time are accounted for.
- Fatigue risk management system
- A systematic approach combining scheduling, reporting, education and controls, used in aviation and rail.
- Microsleep
- A brief involuntary lapse into sleep lasting seconds, frequently unrecognised by the person experiencing it.
- Sleep debt
- Cumulative shortfall against sleep need, which accumulates across consecutive shifts and is not cleared by one long sleep.
FAQ
Frequently asked questions
Does hours of service compliance mean a driver is fit?+
No. Hours rules set a maximum on duty time; they do not measure sleep obtained, time awake, circadian timing, workload during the shift or commute at either end. A driver can be fully compliant, on paper and in an electronic log, and substantially impaired. Compliance is a legal position rather than an assessment of fitness.
What matters more than total hours?+
Consecutive nights, turnaround length, time awake, rotation direction and predictability. A compliant week of consecutive nights with short turnarounds produces more impairment than a longer week of day shifts, because sleep opportunity and circadian alignment matter more than the arithmetic of duty hours.
How do we account for hours we cannot see?+
Partly by asking and partly by design. Ask about time awake at dispatch, which is one field and cannot be reconstructed afterwards. And build rosters with enough recovery that a normal commute and ordinary life do not push someone into impairment, because you will never have complete visibility of second jobs, caring responsibilities or travel.
How should fatigue reports be handled?+
As hazard reports with no penalty attached. The response is redeployment away from safety-critical work for that shift and an examination of what produced the fatigue. Where reporting costs earnings or triggers a performance conversation, it stops within weeks, and the organisation is left assessing a roster instead of a workforce.
What is the most useful analysis we are probably not doing?+
Plotting incidents and near misses by hour of shift and by position in the roster cycle. Most organisations hold the data and have never cut it that way. The pattern, where it exists, is usually visible immediately and points at specific shifts rather than at individuals.
The agents
What the agents do with it
The assessment covers schedule, task and person. What fails is the actual hours nobody captured and the report that cost someone money.
Holds the assessment against rosters and actual duty, captures time awake at dispatch, and flags call-outs and swaps that extend the working day.
Plots incidents and near misses by hour of shift and roster position, surfacing patterns that sit unexamined in existing data.
Routes fatigue reports to welfare and redeployment rather than to performance management, keeping the reporting route usable.
Identifies safety-critical tasks scheduled in the circadian low and prompts rescheduling or additional control.
This template lives in KnowFleet — fleet and transport. Drivers, vehicles, hours, cargo securement and operator licence compliance.
Sources
Sources
- 49 CFR Part 395, hours of service of drivers, FMCSA
- NSC Standard 9, hours of service (Canada)
- HSE HSG256, managing shiftwork: health and safety guidance (GB)
- ISO 39001, road traffic safety management systems
- ISO 45001:2018 clause 6.1.2, hazard identification including work organisation