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Firefighters taking a nap where they can while on deployment.

Sleep deprived but getting the job done

After 17 hours without sleep, impairments in your mental performance are similar to those of blood alcohol levels of 0.05. Your reflexes are slower, your judgement is impaired and what is worse, you may not even be aware of your own impairment, making you potentially more reckless as well. Sleep deprivation/restriction and its effects are often ignored, but can be the ‘quiet thief’ of our intellect and judgement when we need them the most.

We don’t allow people to drive with even slight alcohol impairment but every year 300,000 Australian volunteers can at any time can be called into a stressful and unpredictable situation to fight bushfire. They are asked to cope with this often while in very unfamiliar surroundings and being deprived of sleep.

There is a strong body of research evidence demonstrating the damaging mental effects of sleep deprivation. However, there is much less research around the physical effects of sleep deprivation. We set out to investigate whether restricted sleep would impair firefighters’ physical function.

In the end the surprising result was that a sleep restricted firefighter could still get on and do the necessary job in a physical sense. This result was not going to cause academic headlines but it’s still important information as we know that in those vital situations where it’s “all hands on deck” we can still rely on the sleep restricted worker to “get the job done”.

Volunteer firefighters make an extraordinary contribution to our community. We owe it to them to ensure that they are protected from this potentially dangerous work. It will not be possible to ensure that every bushfire volunteer gets all the sleep they need for optimum performance. Critically though, we should ensure that those who are making important judgements should ideally be well rested, and we need to recognise the physical and mental limitations of the sleep deprived worker, so that we can safely allocate their work and responsibilities.

Volunteer firefighters undergoing physiological testing during a simulated bushfire deployment.

Volunteer firefighters undergoing physiological testing during a simulated bushfire deployment.

Bushfires continue to ravage and cripple communities across the world. With increasingly hot weather predicted, many forecast that the severity and frequency of these devastating bushfire events will continue to rise. Increased bushfire frequency and severity, requiring longer shifts and more frequent deployments, mean the demands on Australia’s fire and emergency service workers are at an all-time high. Therefore, preserving firefighters’ health and safety relies on a robust and occupation-specific evidence base from which to develop policy and best practice.

On the fireground, firefighters face a number of occupational and environmental stressors. They can work long hours during both day and night shift, often with little rest between consecutive shifts. Across each shift, firefighters are required to perform intermittent, intense physical work, often in hot and smoky conditions, whilst remaining alert and vigilant to make critical decisions in life threatening situations and/or amid the personal suffering of others. Restricted sleep represents a potentially modifiable risk factor within this occupation, which had up until our recent program of research, received little attention. Elevated and unsustainable levels of firefighter fatigue and/or degradation of firefighters’ physical work performance could increase their individual risk of injury, increase demand on other crew members, and compromise the overall bushfire suppression operation.

Over the last five years our research team at Central Queensland University and Deakin University, have conducted industry-specific research to assist the fire industry in developing comprehensive policy, best practice guidelines, and educational materials to preserve the health and safety of firefighters during multi-day bushfire suppression deployments. Under the guidance of lead researchers Professor Ferguson and Associate Professor Aisbett, Dr Grace Vincent began her doctoral research in 2012, investigating the interplay between firefighters’ sleep, physical activity, and physical work performance. This was achieved by conducting three studies; two in the field (during actual bushfire suppression), and one in the laboratory (a simulated bushfire suppression deployment). This work, funded by the Bushfire Co-operative Research Centre, investigated the impact of a multitude of risk factors to firefighters’ workplace performance, health, and safety.

Prior to this work, the existing research assessing firefighters’ sleep during bushfire suppression was limited and based exclusively on self-report measures of sleep. Given the known adverse effects of sleep on various physical and mental processes, we wanted to objectively quantify firefighters’ sleep during bushfire deployments. In addition, we aimed to identify specific shift characteristics (e.g., shift length, shift start time, sleep location etc.) that influenced firefighters’ sleep. Sleep was determined using wrist worn activity monitors that accurately detected sleep from wake. This work provided for the first time evidence that firefighters’ sleep was restricted during multi-day bushfire suppression compared to days not fighting bushfire. Of the 40 firefighters who participated in this study, 8% had less than 4 hours of sleep, 51% between 4-6 hours of sleep, 51% between 6-8 hours sleep and 6% greater than 8 hours. Furthermore, total sleep time was reduced when firefighters’ slept in tents or vehicles, completed shifts longer than 14 h, or when their shifts started between 0500–0600 h. Therefore, given that sleep quantity was reduced on days fighting bushfire, fire agencies should focus on modifying specific characteristics of work shifts (e.g., shift length, shift start time, sleeping location) to improve firefighters’ sleep quantity during deployments.

Volunteer firefighters performing physical tasks during a simulated bushfire deployment.

Volunteer firefighters performing physical tasks during a simulated bushfire deployment.

Following this work, it was important to establish whether sleep duration influenced firefighters’ physical activity levels (amount of physical movement performed) during real bushfire suppression, as reduced physical activity could risk firefighters’ health and safety. The data suggested that the sleep duration between shifts did not influence firefighters’ shift-to-shift physical activity levels.

While both of these initial studies utilised validated objective measures to examine firefighters’ sleep behaviour and physical activity levels during actual bushfire suppression, it was difficult to determine physical task performance on firefighting work tasks in this field setting. This was due, in part, to the bushfire environment, which inherently contains variables that may also influence firefighters’ work performance or sleep (e.g., heat, smoke etc). Thus it was difficult to accurately ascertain how restricted sleep directly impacted firefighters’ performance on physical work tasks. In response, we designed, alongside key fire industry advisors, a bushfire work task simulation, to quantify the effects of sleep restriction on firefighters’ physical task performance. We then wanted to determine how firefighters’ work would be influenced when firefighters had 4 hours of sleep (sleep restricted) compared to a full nights rest (8 hours). Under these simulated conditions, 4 hours of sleep restriction did not adversely affect firefighters’ physical task performance on work tasks, compared to those firefighters who received an 8-hour sleep opportunity. However, the sleep-restricted group were less physically active during periods of non-physical work compared to the control group, indicating they may have conserved effort during periods of rest to ensure they were able to maintain performance on firefighting work tasks. This suggests that fire agencies should encourage firefighters to take regular rest breaks, and where feasible, rotate work tasks throughout multi-day deployments, when firefighters sleep is restricted.

The collective findings of our work suggest that while firefighters’ sleep is restricted, it does not appear to adversely affect physical task performance during simulated bushfire suppression. In other words when firefighters are sleep restricted, they are able to still get the job done. Fatigue risk management strategies should prioritise the mental aspects over the physical requirements of firefighting performance. In situations where these factors cannot be modified, fire agencies should identify those firefighters at the greatest fatigue-related risk and implement appropriate controls to manage this risk, so these workers can still work, as necessary, to support the bushfire suppression effort. In addition, under conditions of severe sleep restriction (4 hours), firefighters’ physical activity was reduced during periods not essential for task completion. An implication for this finding may be that firefighters are less likely to return to the staging area to conduct key tasks (e.g., adequately hydrate, check weather maps etc.), which are important to protect them against future risk.

For fire agencies to continue to defend local communities against bushfire, it is critical that a high level of investment in preserving the health and safety of firefighting personnel is maintained. This includes implementing strategies to improve and manage firefighters’ sleep and reduce any adverse impacts that restricted sleep may have on firefighters’ work. This research provides fire agencies with cutting edge information to make evidence-based decisions on workforce planning and provides a platform when developing risk controls. In turn, this may reduce firefighters’ exposure to an environment that contains inherent health and safety dangers.

The next area of focus for the researchers at Central Queensland University and Deakin University is the impact of on-call work on sleep, stress, and next day performance. Australia’s 300,000 strong emergency services volunteers are regularly on-call to respond to high-risk, safety-critical incidents such as fire, flood, search and rescue and road crashes. While sleep during on-call periods is disrupted when a call occurs, some research suggests that sleeping with ‘one ear open’ waiting for a call may disrupt sleep even if no call occurs. If on-call sleep is less restorative, then personnel may be at risk of performance impairments and adverse health outcomes. Thus, this ongoing research will investigate the influence of stress and sleep during on-call periods and the subsequent impact on next day performance.

For more information, email g.vincent@cqu.edu.au

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Dr Grace Vincent is a Senior Postdoctoral Research Fellow at the Appleton Institute, CQUniversity. Grace was a recipient of a three-year Bushfire Co-operative Research Centre PhD scholarship, and completed her doctoral thesis at Deakin University in 2015. Grace is currently investigating the impact of working ‘on call’ on sleep, stress, and next day work performance.