Heavy vehicle operators are being urged to look beyond whether drivers feel sleepy when assessing fatigue, with work schedules, recovery time and sleep quality all influencing safety behind the wheel.
Katrina Aubrey, Fatigue & Sleep Health Specialist at AutoSense, says experienced, safety-conscious drivers can struggle to recognise when fatigue is affecting their performance.
“I describe fatigue as your brain and body running on a low battery. You can still function, but everything requires more effort,” Aubrey says.
“Your attention, decision-making and reaction times suffer, even if you don’t necessarily feel sleepy.”
For fleet managers, that creates a challenge: a driver who says they feel fine may still be experiencing reduced alertness.
Why early starts need closer attention
Aubrey explains that two biological processes largely determine alertness: the body clock and sleep pressure.
The body clock naturally promotes wakefulness during the day and sleep at night, with the drive for sleep particularly strong between approximately 2am and 6am. Sleep pressure builds the longer someone remains awake and is relieved through sleep.
For drivers working overnight or starting before dawn, those processes can combine at a time when the job demands sustained concentration.
“Fatigue isn’t simply a matter of drivers taking responsibility and getting more sleep,” Aubrey says.
“Shift patterns, long working hours, recovery opportunities and underlying health conditions all influence how alert someone is behind the wheel.”
The implication for transport operators is that fatigue management needs to include how work is planned, alongside individual driver behaviour.
Time in bed doesn’t tell the whole story
Aubrey says recurring fatigue can also indicate an underlying sleep problem, even when a driver appears to have sufficient time to rest.
Obstructive sleep apnoea, which causes repeated interruptions to breathing during sleep, is one condition she highlights as particularly relevant to the transport industry.
Some people feel exhausted after spending eight hours in bed, while others may not recognise obvious symptoms.
“One saying I regularly use is, ‘Do not ignore the snore.’ Loud, persistent snoring, particularly when accompanied by pauses in breathing, is worth investigating with a GP or sleep specialist,” Aubrey says.
For managers, repeated fatigue events should prompt a supportive conversation about possible causes.
“If a driver is repeatedly fatigued despite apparently getting enough sleep, we need to be curious rather than judgemental. Could something else be going on?”
Temporary fixes have limits
Aubrey recommends protecting sleep through a cool, dark and quiet sleeping environment, particularly for shift workers resting during daylight hours.
She also points to caffeine and alcohol consumption near bedtime, screen use and bright light as factors that can affect sleep.
During a shift, a short nap or caffeine may temporarily improve alertness, while movement or a change of task can help counter monotony. However, she stresses that these measures cannot replace adequate sleep.
“If a driver becomes sleepy behind the wheel, the safest action is to stop driving in a safe location and take appropriate rest before continuing,” Aubrey says.
Use fatigue alerts to start a conversation
In-vehicle monitoring can help operators identify drowsiness, but Aubrey says detecting an event is only part of effective fatigue management.
Operators also need to examine whether schedules allow sufficient recovery, whether a sleep disorder could be involved and whether drivers feel comfortable reporting fatigue.
For heavy vehicle fleets, the value of an alert extends beyond the immediate intervention. It provides an opportunity to investigate contributing factors and improve support before another event occurs.
“Ultimately, the sleep we get tonight influences the brain we bring to work tomorrow,” Aubrey says.
“It determines how well we concentrate, react and make decisions.”
