The Future of Fatigue

Imagine asking an Operations Director: “Why did nothing go wrong today?”

It sounds like an odd question. We are much more accustomed to asking the opposite. Why did the incident happen?

After time, incidents and errors lead to this question: Why did another experienced employee leave? But what if the future of fatigue management is less about waiting for fatigue to become visible through an incident, absence or resignation and more about understanding the conditions that allow people to perform safely every day?

Because our understanding of fatigue is changing. Fatigue isn’t simply an empty battery, or solved by telling someone to get an early night.

The future, I believe, is multidimensional, systemic and proactive and several areas of psychology, physiology and human factors help explain why.

We already know fatigue is an organisational risk. The starting point isn’t particularly controversial.

The UK’s Health and Safety Executive (HSE) describes fatigue as a decline in mental and/or physical performance associated with factors including prolonged exertion, sleep loss and circadian disruption. It identifies consequences including slower reactions, reduced information processing, memory lapses, decreased awareness and attention, and underestimation of risk.

HSE also recognises workload as important: complex, monotonous and machine-paced work can contribute to fatigue. More than 3.5 million people in the UK work shifts, across sectors including healthcare, emergency services, utilities, transport and manufacturing.

HSE explicitly warns that poorly designed shifts and long working hours without adequate rest and recovery can contribute to fatigue, accidents, injuries and ill health.

So we know fatigue matters. The interesting question is: Are we measuring and managing the right things?

The battery metaphor has its limits. You start the day at 100%, work drains you, rest recharges you and It’s wonderfully simple.

It’s also incomplete. One reason comes from the Central Governor Model, most associated with Professor Tim Noakes’ work on exercise fatigue. Rather than treating fatigue purely as the point at which the muscles physically run out of energy, the model proposes a regulatory role for the brain: perceived fatigue and changes in effort help regulate behaviour in order to protect physiological homeostasis.

In Noakes’ account, fatigue is therefore partly a brain-derived protective experience, rather than simply evidence that the body’s fuel tank has reached empty.

That theory originated in exercise physiology and remains debated, so we should be cautious about simply transplanting it into workplace fatigue. But the underlying idea is fascinating for organisations: What if fatigue is sometimes information?

What if the urge to slow down, disengage or stop isn’t simply an employee failing to be resilient enough?

“What is their system responding to?”

Motivational Control Theory takes us even further. Glyn Hockey’s Motivational Control Theory of cognitive fatigue challenges the energy-depletion metaphor from another direction.

Hockey proposed that fatigue can be understood as an adaptive state involved in managing goals and control.

Think about your own experience.

You can spend two hours struggling through a tedious spreadsheet and feel completely drained. Then somebody suggests doing something you genuinely care about and, strangely, you discover another reserve.

Did your mental battery suddenly recharge? Well probably not.

Motivation, goals, perceived value, control and competing demands matter and this has enormous implications for work.

An employee saying “I’m exhausted” may be describing something far more complicated.

Perhaps maintaining attention has become increasingly effortful and they’re constantly switching tasks, conflicting priorities and demands of the job require continuous self-regulation.

They’re investing increasing amounts of effort simply to maintain what looks externally like normal performance and that is particularly important.

Good performance can hide fatigue. This is where Hockey’s earlier Compensatory Control Model becomes incredibly useful. Under high workload or stress, people can dynamically allocate additional effort to protect important performance goals. In other words, observable performance can sometimes be maintained but at an increasing cost.

That should make every leader interested in fatigue slightly uncomfortable. Because we often use performance as reassurance.

“They’re still hitting their targets.”

“Nothing has gone wrong.”

“The team is coping.”

But what effort is required to keep achieving that?

Someone might maintain their output by concentrating harder, skipping breaks, staying late, double-checking everything, suppressing frustration or sacrificing less important tasks.

From the outside, the system appears successful, but on the inside people may be working increasingly hard to stop it failing.

Eventually something gives; performance, wellbeing, patience, safety or the employee simply leaves.

So perhaps one of the future questions of fatigue management should be: “What is it costing them to maintain that performance?”

This is where Safety-II becomes fascinating

Traditional safety management is often described through what Erik Hollnagel calls Safety-I: we study unwanted outcomes and try to prevent them happening again. Safety-II adds another question: How does work go right under varying conditions?

Hollnagel argues that safety should involve understanding the adjustments that allow everyday work to succeed, rather than learning only from the relatively small number of occasions when something goes wrong.

Bring fatigue into that conversation. Imagine asking your Operations Director: “Why did nothing go wrong today?”

Perhaps they’ll laugh.

Maybe the answer is that an experienced employee noticed a colleague struggling and took over part of their workload, someone delayed a non-essential task, a supervisor moved people around, staff members unofficially task swapped at certain points in a night shift because they know when concentration drops or someone took an extra coffee break, this are all evidence that the team has developed informal practices that aren’t written anywhere but help them keep the operation safe.

Those adaptations are incredibly valuable information. But they can also reveal that your system is safe because it is well designed, or because your people are exceptionally good at compensating for its weaknesses?

HSE’s human-factors approach fits naturally with this systems thinking. It emphasises the interaction between the job, the individual and the organisation, including workload, task demands, equipment, procedures, working patterns and the wider organisational system.

That’s a much richer way of thinking about fatigue than simply counting hours worked.

There may not be one fatigue!

This is perhaps the development I’m most interested in. Imagine asking: “How healthy are you?” and expecting a single number to explain everything.

Fatigue can be physical with heavy limbs, reduced strength and physical exhaustion. But it can also be cognitive with difficulty concentrating, slower thinking, forgetfulness and decision fatigue. It can also be emotional, feeling depleted by interactions, emotional demands or the continuous requirement to regulate how you respond.

The Three-Dimensional Work Fatigue Inventory is one example of research treating work fatigue as multidimensional, separately assessing physical, mental and emotional work fatigue rather than collapsing the experience into one score.

More recent occupational measurement work is pushing dimensionality further; for example, a 2025 healthcare-worker fatigue scale distinguished physical, cognitive/emotional, social, sleep-related and auditory dimensions.

This matters enormously.

A paramedic after physically demanding calls may have a very different fatigue profile from a control-room operator monitoring screens overnight.

A nurse carrying repeated emotional interactions may be depleted differently from an engineer making safety-critical decisions after an emergency call-out.

One intervention won’t necessarily solve all four.

Coffee doesn’t fix emotional exhaustion, sitting down doesn’t necessarily restore cognitive capacity and a webinar doesn’t create sleep opportunity after an overnight call-out.

If fatigue is multidimensional, our interventions need to become more precise.

So what does the future of fatigue management look like?

I think we need to move beyond simply asking:

How many hours did they work?

Hours matter enormously. But they’re not the whole system.

HSE itself warns against treating hours-of-service limits as the entire solution. In its statement on fatigue risk management systems, it notes that limits can act as triggers for further risk assessment and cautions that consistently working to limits is not sustainable.

The next generation of fatigue management should therefore combine objective conditions with lived experience and operational context.

That means examining working hours and sleep opportunity alongside workload, cognitive demand, emotional demand, predictability, autonomy, staffing, interruptions, call-outs, recovery, commuting, task criticality and the compensatory behaviours employees use to keep work functioning.

It means training managers not simply to recognise somebody yawning, but to notice changing behaviour, increasing effort and deteriorating capacity.

Continuous learning from successful days as well as incidents and measuring fatigue across multiple dimensions is important! Rather than relying entirely on a single question asking employees how tired they feel.

Most importantly, it means treating fatigue as information about the relationship between people and the system in which they’re working.

So review the workload, look at the recovery opportunities, talk to the people actually doing the work, understand the adaptations keeping the operation functioning, train managers, look beyond compliance, measure cognitive, emotional and physical fatigue and investigate the conditions surrounding success.

Perhaps the most interesting fatigue data in your organisation isn’t sitting in an absence spreadsheet or incident report, it might be hiding in all those ordinary days when exhausted people adjusted, compensated and worked harder… and somehow nothing went wrong.

Georgia Hodkinson is an Organisational Psychologist specialising in fatigue, human factors and work design. She helps organisations identify the hidden fatigue risks behind errors, absence, poor performance and turnover, and turn psychological research into practical changes that help people work safely and sustainably.

Georgia Hodkinson GMBPsS

Further reading

The key foundations behind this article include HSE's workplace fatigue guidance⁠, HSE's Managing Shift Work guidance (HSG256)⁠, Hockey’s Compensatory Control framework⁠, the Three-Dimensional Work Fatigue Inventory research⁠ and Erik Hollnagel’s Safety-I and Safety-II.