Working on a roster means weeks on site, often on 12-hour shifts that switch between days and nights. In between come long journeys to and from site, sometimes by air, road, and boat in a single day. All of this can cut into sleep and make proper rest hard to get.

The result is work fatigue. Fatigue is more than feeling tired. It lowers alertness and slows reactions, and on a site full of heavy equipment, vehicles, and machinery, even a small drop can lead to an accident. This article covers the signs of fatigue, why roster workers face a higher risk, and what workers, supervisors, and the site clinic can do.

What work fatigue is

According to NIOSH, the US occupational health institute, fatigue at work is most often linked to non-standard schedules that disrupt or shorten sleep, such as night shifts and long hours. Other factors play a part too: stress, physically or mentally demanding tasks, and working in hot environments.

The effects go beyond sleepiness. NIOSH notes that fatigue can slow reaction times, reduce attention and concentration, limit short-term memory, and impair judgement. It can affect anyone, in any job.

Signs of fatigue

People who are fatigued often do not notice it themselves. That is why it matters to recognise the signs in yourself and in your workmates. OSHA, the US workplace safety agency, says fatigue can cause weariness, sleepiness, irritability, reduced alertness, poor decisions, and a lack of motivation, concentration, and memory.

On site, these signs can look like this:

  • constant yawning, heavy eyes, or head nodding;
  • trouble focusing, drifting off, or having to reread instructions;
  • forgetting work steps that are normally second nature;
  • slow reactions, such as braking late or missing a radio call;
  • being quicker to anger than usual;
  • falling asleep for a moment without realising, especially while sitting still, driving, or operating equipment.

This list is to help you spot patterns, not to diagnose yourself or anyone else. Tiredness that persists even after enough sleep can be linked to other health conditions and should be checked by the medical staff on site.

Why roster workers face a higher risk

Night shifts

The body has a biological clock that naturally makes us sleep at night. Working at night and sleeping by day goes against that clock, so daytime sleep is often shorter and lighter. According to research cited by OSHA, accident and injury rates are about 18% higher on evening shifts and 30% higher on night shifts than on day shifts. Working 12 hours a day has also been linked to a roughly 37% higher risk of injury.

The body also needs time to adjust whenever the shift pattern changes. So the first few days after switching from days to nights call for extra care.

Long journeys

The trip to site can start before dawn and end late at night. If a worker goes straight onto shift after arriving, they start work already short of sleep. The same happens at the end of a roster: a worker who has just finished a night shift and heads straight home, especially if driving themselves, risks falling asleep on the road. OSHA cites research showing that long shifts increase the risk of vehicle crashes on the way home.

Work environment

Heat, noise, and heavy physical work add to the load on the body. In hot areas such as smelters, fatigue and heat stress often appear together. Heat is covered in our article on heat stress at smelters.

Controlling fatigue

Workers cannot solve fatigue on their own. Work schedules, camp conditions, and site culture all play a part.

Sleep schedule and habits

OSHA recommends several healthy sleep habits, including:

  • sleep 7–9 hours a day without interruption, ideally at the same time each day;
  • avoid caffeinated drinks before bed;
  • if working evenings or nights, make sure you have slept within the 8 hours before starting work;
  • if napping before work, keep it under 45 minutes or over 2 hours so you do not wake mid-cycle;
  • sleep in a comfortable, cool, dark, and quiet room.

For night-shift workers, a camp room that stays dark and quiet during the day helps a great deal. This is the company's responsibility too, for example through blackout curtains, noise control around the camp, and separate accommodation blocks for night-shift workers where possible.

If you have ongoing trouble sleeping, do not treat it yourself with medication without first speaking to the site clinic doctor.

Pre-shift fatigue checks

A short check before each shift can be run for workers in high-risk roles, such as heavy equipment operators and drivers. The questions are simple, for example:

  • how many hours have you slept in the last 24 hours, and in the last 48 hours;
  • how many hours have you been awake since you got up;
  • have you just arrived from a long journey;
  • are you unwell or taking any medication that can make you drowsy.

The answers are read together with the supervisor's observations. If a worker seems too tired, options include resting first, a temporary move to lower-risk work, or an assessment by medical staff. The aim is not to punish anyone but to prevent accidents.

The supervisor's role

Supervisors see workers more than anyone before and during a shift. Their role includes:

  • building schedules that allow for breaks and enough night-time sleep, and avoiding excessive overtime;
  • not putting workers who have just arrived from a long journey straight onto a night shift or a critical task;
  • rotating monotonous, high-risk tasks;
  • making it safe for workers to report that they are fatigued, without fear of a reprimand or lost pay.

The site clinic's role

The site clinic can help by assessing workers reported as too tired, looking for possible medical causes, and educating workers about sleep and fatigue. It can also record fatigue cases by area and job type, so patterns show up and can be discussed with the HSE team.

At company level, OSHA recommends reviewing workload, working hours, and understaffing, adjusting the work environment such as lighting and temperature, training on fatigue, and adopting a fatigue risk management plan that treats fatigue like any other OHS risk.

A fatigue control program can run as part of our occupational health service, supported by an onsite clinic for pre-shift checks and day-to-day care on site.

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