Aware Labs
How fatigue affects decision making on shift
Have you ever felt completely fine… but then made a really simple mistake?
You forget something obvious. Say something that doesn't quite land. Miss a step you normally wouldn't.
And it makes you pause and think, what was that?
I've had that happen more times than I'd like to admit.
Especially on longer shifts or after multiple back-to-back jobs, I've found myself forgetting simple things, losing track of details, or double-checking tasks I'd normally do without thinking.
At first, I brushed it off.
But once I started paying attention, I realised it wasn't random.
It showed up far more often when I was:
• Sleep deprived
• Mentally overloaded
• Coming off high-intensity work
That's when I started looking deeper into what fatigue actually does to performance.
What fatigue actually does to your brain
Fatigue doesn't just make you feel tired. It directly affects how your brain processes information and makes decisions.
Research shows fatigue impacts:
Attention and focus
Sustained attention drops with sleep loss.
You're more likely to:
• Miss small details
• Overlook risks
• React slower to changes
Decision making
Fatigue affects judgement and decision-making.
This can lead to:
• Slower decisions
• Less accurate judgement
• Reduced ability to adapt under pressure
Memory and task execution
Working memory declines early under fatigue.
This affects your ability to:
• Hold information in the moment
• Follow multi-step tasks
• Stay on track
You're more likely to forget steps or lose your place mid-task.
Reaction time and motor control
Fatigue slows reaction time and reduces coordination.
Being awake for around 17–19 hours can impair performance to a level comparable to a blood alcohol concentration of 0.05%.
That's measurable performance decline, not just feeling tired.
Why it catches you off guard
Fatigue doesn't always feel like fatigue.
You can feel alert and functional while your performance is already reduced.
That's where the risk sits.
Instead of obvious warning signs, it shows up in small moments:
• A missed detail
• A delayed response
• A simple mistake
Where this shows up on shift
In real terms, this can look like:
• Forgetting equipment or steps
• Needing to double-check things
• Slower processing under pressure
• Difficulty tracking multiple tasks
Individually small, but important in the wrong moment.
My perspective on it now
Once I started understanding fatigue properly, I saw it everywhere, especially in myself.
What changed wasn't trying to push through it better, but recognising when it was likely to be happening.
When I know I'm fatigued, I:
• Slow things down slightly
• Double-check more deliberately
• Stay more aware of small details
Once I started tracking and understanding my fatigue in real time, I found I could stay more consistent in how I performed.
Not perfect, but more aware.
The takeaway
Fatigue doesn't just make you feel tired.
It changes how you think, decide, and perform.
You won't always feel it happening, but if you understand when it shows up, you give yourself a much better chance of catching it before it catches you.