Heavy vehicle driver fatigue (micro-sleep)

The purpose of this Safety Alert is to highlight the importance of an effective fatigue management system for drivers of heavy and light vehicles and other mobile plant that may momentarily fall asleep (micro-sleep) and lose control of the vehicle while at work.


NT WorkSafe has received a number of incident notifications of light and heavy vehicle accidents at or near mine sites, some resulting in serious injuries. Many of these involved fatigue and reported micro-sleep.

Micro-sleep is an episode of sleep which may last for a fraction of a second or up to thirty seconds. Often, it is the result of sleep deprivation, mental fatigue, depression, apnea, hypoxia, narcolepsy, or hypersomnia. In many circumstances these can be attributed to fatigue.

For the sleep-deprived, or the fatigued, micro-sleeping can occur at any time without warning.

Contributing factors

Micro-sleeps become extremely dangerous as you stop responding to events around you. Your brain has, in some sense, turned off for a few moments. This can occur in situations which demand constant alertness such as driving a motor vehicle, road train or operating heavy mobile plant. There is generally a higher risk with longer working hours and on a variable shift.

Factors such as long working hours, consecutive night shifts or altered shift patterns, multiple rostered days on/off, activities requiring higher levels of physical or mental activity, can create a high fatigue risk, either individually, or in combination. Development of appropriate fatigue management systems which attempt to eliminate or minimise fatigue hazards can effectively reduce the risk.

Action required

Mine operators, workers and contractors all have a responsibility to participate in the control of fatigue: Monitoring hours of work, ensuring adequate rest and meal breaks, encouraging self-reporting and self-assessment for fitness to work can all assist in the reduction of fatigue risks.


  • need to plan the transport task to minimise fatigue through a regular risk assessment process
  • have a duty of care to ensure drivers are fit for work.


  • need to follow fatigue management and trip procedures that have been designed to reduce safety risks associated with fatigue
  • being fit for work at the start of a shift and during a shift is a major contribution that you can make towards a safe environment
  • manage your time between shifts and your lifestyle in a responsible way in an effort to prevent fatigue. It is your obligation.

This Safety Alert contains safety information following inquires made by NT WorkSafe about an incident or unsafe practice. The information contained in this Alert does not necessarily include the outcome of NT WorkSafe’s action with respect to an incident. NT WorkSafe does not warrant the information in this Alert is complete or up-to-date and does not accept any liability for the information in this report or as to its use.