Peak Physiology | Occupational health and injury prevention for Hunter businesses

Most workplaces treat fatigue as a personal problem. Someone turns up flat, gets a comment about a late night, and the shift rolls on. But fatigue is not a lifestyle issue that workers bring through the gate. It is a workplace hazard produced largely by how work is designed, rostered and resourced, and it sits squarely inside an employer’s work health and safety duties.

The reason fatigue gets overlooked is that it rarely appears in an incident report. It appears as the reason behind the incident. The worker who misjudged the load. The operator who missed the step in the isolation procedure. The driver who drifted. Fatigue is almost never recorded as the cause, because by the time an investigation happens, everyone is looking at the action rather than the state the person was in when they took it.

What fatigue actually is

Fatigue is more than feeling tired. It is a physical and mental state of reduced capacity that impairs a person’s ability to perform work safely and effectively. It builds from a combination of sources, and in industrial workplaces those sources usually stack:

• Sleep loss and poor sleep quality — both the total hours and how broken the sleep is
• Time awake — after roughly 17 hours of continuous wakefulness, performance degrades to a level comparable with a blood alcohol concentration of 0.05
• Time of day — the body’s circadian low points sit between roughly 2am and 6am, and again in the mid-afternoon
• Workload and task type — sustained physical exertion, high mental load, and monotonous work all accelerate fatigue
• Environmental conditions — heat, noise, vibration and poor lighting all increase the physiological cost of the same task

A worker can get eight hours of sleep and still be fatigued if they have been doing heavy repetitive work in 34 degree heat for six hours. Sleep is one input, not the whole picture.

What fatigue does to injury risk

Three effects matter most for safety.

Reaction time slows. The gap between recognising a hazard and responding to it lengthens. In dynamic work — moving plant, load handling, traffic interaction — that gap is the whole margin of safety.

Attention narrows and lapses. Fatigued workers experience micro-lapses in attention, brief moments where they are physically present but not processing. They frequently do not notice these lapses happening.

Decision making degrades in a specific way. Fatigued people do not simply make more mistakes at random. They become more likely to accept a risk they would normally decline, and more likely to take the shortest path rather than the correct one. This is why fatigue-related incidents so often look like deliberate procedural breaches after the fact.

There is also a musculoskeletal effect that gets far less attention. As muscles fatigue, movement quality changes. Lifting technique deteriorates, load transfers from larger muscle groups to smaller stabilising structures, and the spine and shoulders take stress they are not positioned to handle. The same lift performed at the start of a shift and at the end of a shift is not the same event. Manual handling injuries cluster towards the end of shifts and towards the end of consecutive shift blocks for exactly this reason.

The warning signs supervisors can actually see

Workers are poor judges of their own fatigue. Once impaired, the capacity to assess impairment is itself impaired. This is why relying on people to self-declare rarely works on its own.

Observable indicators that are worth training supervisors to notice:

• Repeating questions or needing instructions restated
• Making uncharacteristic errors on familiar tasks
• Slowed movement, or conversely, rushed and jerky movement
• Withdrawal from conversation, or unusual irritability
• Difficulty maintaining a conversation, frequent yawning, heavy blinking
• Standing still and staring, particularly during monotonous tasks

None of these on its own proves fatigue. A cluster of them in someone who is normally sharp is worth a conversation.

A simple self-check that works

Self-assessment is imperfect but not useless, particularly when it is structured. A traffic light check at pre-start takes thirty seconds:

Green — fit for work. Adequate sleep, feeling alert, no significant fatigue sources stacked.

Amber — monitor. Short on sleep, coming off a heavy block, or feeling flat. Continue, but flag it, avoid the highest-risk tasks where possible, and check in again mid-shift.

Red — talk to someone. Significantly under-slept, unable to concentrate, or aware that you would not want a family member driving with you. This requires a conversation before work starts, not after something happens.

The value of this is not the categories. It is that it makes fatigue a normal thing to say out loud. In workplaces where nobody has ever raised fatigue, the first person to do it carries a social cost. A structured check removes that cost.

Shift workers: what actually helps

Shift work is a hazard that cannot be eliminated in most industrial settings, so it has to be managed. The controls that carry the most weight sit with the organisation, not the individual:

• Roster design — forward rotation (day to afternoon to night) is tolerated better than backward rotation, and limiting consecutive night shifts reduces cumulative sleep debt
• Break scheduling — short, frequent breaks are more protective against fatigue-related error than one long break
• Task allocation — scheduling the highest-risk and most cognitively demanding tasks away from circadian low points
• Commute risk — the drive home after a night shift is often the most dangerous part of the shift, and is rarely managed at all
• Overtime governance — informal overtime that nobody tracks is where fatigue exposure hides

Individual sleep strategies still matter, and workers deserve good information about them: a consistently dark and cool sleep environment, avoiding caffeine within roughly six hours of intended sleep, a wind-down routine, and treating day sleep with the same protection as night sleep, including telling the household it is not optional. But sleep hygiene advice given to a worker on a poorly designed roster is a control at the very bottom of the hierarchy. It should never be the only thing an employer does.

What good fatigue management looks like

Under the Work Health and Safety Regulation 2025 (NSW), a PCBU must manage risks to health and safety so far as is reasonably practicable, and must apply the hierarchy of controls. Fatigue is a risk like any other. A fatigue policy sitting in a folder is not a control. Practical management looks like:

1. Identifying where fatigue exposure genuinely sits — which rosters, which tasks, which times
2. Consulting workers, who almost always know exactly where the problem is
3. Changing what can be changed at the design level: rosters, workload, task scheduling, break structure
4. Building supervisor capability to recognise and respond to fatigue without it becoming a disciplinary event
5. Reviewing after changes, and after any incident where fatigue may have been a factor

If you are struggling personally

Persistent fatigue that does not resolve with rest can have medical causes, including sleep apnoea, which is common and often undiagnosed in shift-working populations. It is worth seeing your GP.

If fatigue is sitting alongside stress, low mood or feeling overwhelmed, support is available:

• Lifeline — 13 11 14 (24 hours)
• Beyond Blue — 1300 22 4636
• Your workplace EAP, if your employer provides one

For workplace WHS advice, SafeWork NSW — 13 10 50.

Where Peak Physiology fits

We work with Hunter, Lake Macquarie and Newcastle businesses to identify where fatigue and physical workload are genuinely creating injury risk, and to design controls that hold up under scrutiny.

If you would like an independent look at one task or one work area in your business, we offer a free workplace assessment for local businesses with 15 or more workers. One task or workstation reviewed, one risk concern discussed, and written recommendations you can act on.

Brock McInerney | Accredited Exercise Physiologist | Peak Physiology