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Whether you’re commuting to work or roadtripping up the coast, driving can be tiring.

That’s because driving is a complex task that requires multiple parts of your brain – including those that help you plan, stay alert, and perceive the world – to work together.

But when you’re tired, these parts of your brain may not function as well. That’s one reason why driver fatigue is such a concern.

Recent research shows drowsy driving contributes to between 20% and 30% of all crashes on Australian roads. And it can affect drivers of all ages and levels of experience.

So how does driving affect your brain? And how can you stay alert while on the road?

The neuroscience of driving

Driving is a complex task that relies on brain regions that control attention and vigilance, perception, motor control and high-level cognition.

One meta-analysis examined existing research about how driving affects brain activity. It found driving requires a surprisingly large number of specific brain regions.

This includes the cerebellum and premotor cortex, two brain regions that help coordinate movement. Also involved is the extrastriate cortex, which processes visual information from the world around you. Driving also activates the thalamus, a part of the brain that helps you stay alert and turn sensory information into physical movement.

Why is driver fatigue so dangerous?

Research suggests driving while you are tired can be just as dangerous as driving under the influence of alcohol. About 20% of all deaths on Australian roads are fatigued-related.

Fatigue is a physiological state of impairment that impacts how well your mind and body function. Specifically, fatigue can negatively affect how well you pay attention, make decisions and respond to your surroundings – all of which are crucial for safe driving.

However, microsleeps are perhaps the most dangerous consequence of driving while tired. A microsleep is a brief, involuntary period of sleep which can last up to 15 seconds.

But even during a three-second microsleep at 100 kilometres per hour, your car may travel more than 80 metres without you being in control. This can have catastrophic consequences if you drift off the road, or into pedestrians or other vehicles.

Time matters

Driving may feel like a task you do automatically. But it does require a high level of sustained attention, especially compared to other activities such as responding to emails, operating machinery, or doing other ordinary work tasks.

If you drive for a long time, you might notice yourself paying less attention over time. That’s because driving takes significant mental effort, with some evidence suggesting fatigue may set in after just 60 minutes of driving.

The longer you’re continuously driving, the more likely you are to make a poor decision or fall into a microsleep. Research suggests this is especially true if you are driving at night or on monotonous roads. And even if you don’t feel tired, you may still make errors because your brain is not fully alert.

So if you have a long drive ahead of you, a good rule of thumb is to break it into two-hour blocks. This limits the amount of time spent driving without a break, which helps to reduce your risk of getting driver fatigue.

Other factors to consider

Several other factors may make you more tired while driving.

One is sleep. Research shows having less than five hours of sleep can double your chances of being in a crash. And being awake for long periods – that is more than 17 hours – is also associated with higher risk of driver fatigue.

Another factor is driving at times when you’d normally be sleeping. This disrupts your circadian rhythm – commonly known as your “body clock” – and may mean you’re more likely to fall asleep at the wheel.

Research suggests stress, parenting a newborn, and not consuming enough water or healthy food may also contribute to driver fatigue.

It’s also worth noting, being an experienced driver doesn’t protect you from fatigue. Research shows experienced drivers are still at risk of getting into a fatigue-related crash. Experienced drivers may also become overconfident and, as a result, may take more risks on the road.

So, how can I stay alert while driving?

It’s crucial to get enough sleep before jumping behind the wheel. To function at their best, adults generally need between seven and nine hours of sleep each night. But to drive safely, you need at least five hours of sleep the night before.

Importantly, there isn’t much evidence to suggest strategies such as winding down your window or listening to music actually fight fatigue.

Instead, when driving long distances, remember to stay hydrated and take regular breaks. And if you’re feeling too tired to drive, take a nap first. You can also share the driving or postpone your trip.

Madeline Sprajcer receives funding from the Australian Research Council.

Alysa Bachmann receives funding from Australian Rotary Health.