Driving Fatigue and Cognitive Overload: A Silent Threat on the Roads

Attention development is closely related to our nervous system, particularly to the maturation of the brain‘s frontal lobe. The development of attention is a gradual process, and its changes are influenced by age, learning environment, personal characteristics, and lifestyle habits.

 

The stages of attention development are divided into three phases: infancy stage (0 to 5 years old), childhood and adolescence stage (6 to 18 years old), and adulthood stage (18 years old and above). According to research published in the Journal of Cognitive Neuroscience, during the infancy stage, the brain is in a phase of rapid development, but its executive functions have not yet fully developed; by adulthood, attention reaches a stable period but still depends on the difficulty of the task and external distractions. Generally, adults can focus for about 20 to 30 minutes, especially during highly cognitive activities such as reading or problem-solving.

 

Studies on the natural fluctuations of attention point out that human attention resources are limited. After focusing, the brain gradually shows signs of fatigue, typically peaking at about 20 to 30 minutes before starting to decline. If forced to continue at this point, it may lead to reduced efficiency and increased error rates. Additionally, dopamine has a relative impact on concentration. When focusing, the dopamine system is activated, enhancing executive functions and goal-directed behavior. However, as the duration of focus extends, dopamine levels may decline, affecting the stability of attention. The frontal lobe, which is the main area for managing executive functions and attention, also has limited resources. Continuous focus gradually increases cognitive load, reducing information processing efficiency.

 

When the frontal lobe’s functions are overloaded, a series of neurophysiological phenomena occur, mainly involving a decline in cognitive functions, an imbalance in neurotransmitters, and weakened functional coordination between brain regions. This will lead to weakened executive functions and cognitive fatigue, causing a decline in a series of executive functions.

 

The frontal lobe is responsible for executive functions such as planning, decision-making, concentration, and working memory. However, when overloaded, these functions gradually weaken, manifesting as reduced decision-making ability, diminished task-switching ability, and transient failures in working memory, which are related to the inability to meet the energy demands of the frontal lobe neural networks. Cognitive fatigue occurs because prolonged concentration increases glucose metabolism in the frontal lobe, causing rapid energy consumption, leading to weakened neural activity and intensified fluctuations in attention.

 

Dopamine release in the frontal lobe is crucial for maintaining concentration. However, in an overloaded state, it may lead to reduced concentration and lower motivation. Long-term overuse of frontal lobe functions may decrease the sensitivity of dopamine receptors, further worsening the instability of attention.

 

When the frontal lobe is overloaded, abnormal changes in brain waves occur. The brain’s EEG spectrum shows excessive activity of high-frequency beta waves, indicating tension and stress, while alpha waves decrease, representing impeded relaxation and recovery of concentration. These changes may lead to difficulties in maintaining attention and increased emotional stress.

 

Frontal lobe overload stimulates the stress-related adrenal axis, leading to elevated cortisol levels. Overactivation of the adrenal axis results in effects such as impaired cognitive functions, emotional fluctuations (e.g., irritability or anxiety), and intensified physical fatigue.

 

The practical behavioral impacts of reduced driving concentration include prolonged reaction times. According to the journal Accident Analysis and Prevention, reduced driving concentration can extend reaction times by approximately 20–30%, particularly in response to sudden situations such as a sudden stop of the car ahead, which can lead to accidents. Another impact is narrowed visual attention. When fatigue or concentration weakens, a driver’s field of vision narrows from broad to focus on a central area, ignoring surrounding vehicles or obstacles, thereby increasing the risk of accidents. Additionally, judgment deteriorates. Attention fatigue impairs the decision-making functions of the frontal lobe, preventing drivers from correctly assessing risks, such as underestimating braking distances at high speeds, thereby increasing the likelihood of dangerous actions.

 

The main causes of cognitive fatigue during driving include prolonged driving. After driving for an average of 1–2 hours, the brain’s attention resources begin to decline, and the driver’s reaction capacity weakens. Monotonous driving environments, such as long periods of driving on highways or in unchanging surroundings, reduce sensory stimulation and easily induce fatigue, which is related to decreased cortical excitation levels in the brain. Multitasking interference, such as simultaneously handling navigation, traffic conditions, and in-car conversations, increases cognitive load, accelerating the onset of fatigue. Sleep deprivation or circadian rhythm disorders lower the activation levels of the brainstem and frontal lobe, leading to unstable attention. Additionally, the American Academy of Sleep Medicine states that if driving time overlaps with the body’s physiological low points, such as midnight to early morning, the risk of fatigue increases significantly.

 

The following case illustrates an accident caused by poor attention:

In 2009, a severe traffic accident occurred in New York State, USA, involving a high-speed commuter bus. The direct cause of the accident was the driver’s distraction due to texting on a mobile phone while driving, which failed to notice the congestion ahead of time. The bus failed to decelerate and ultimately collided at high speed with multiple vehicles. This accident led to the deaths of several passengers and injuries of varying severity to dozens more. The investigation report revealed that the driver’s visual, manual, and cognitive attention was diverted by mobile phone use, preventing accurate assessment and response to the current road conditions. This accident highlighted the dangers of distracted driving, particularly the impact of smartphones on drivers. Operating a phone requires drivers to divert their eyes from the road, remove their hands from the steering wheel, and shift their focus away from their surroundings. These three types of distractions were the critical factors contributing to the tragedy. This incident prompted the U.S. Department of Transportation to strengthen warnings and legislative controls against distracted driving, including the enactment of laws prohibiting mobile phone use while driving. The accident became a significant reminder for drivers to prioritize attention management and spurred higher safety standards within the public transportation industry.

 

In 2014, a severe intercity train collision occurred in Daejeon Metropolitan City, South Korea. A high-speed train failed to adhere to a red warning signal and ultimately collided with the train ahead. The accident resulted in multiple fatalities and injuries to hundreds of passengers, some of whom suffered severe wounds, significantly impacting the transportation system. The investigation revealed that the driver was in a state of severe fatigue after extended working hours, leading to a significant decline in attention. The driver failed to detect and respond to the warning signal in time, preventing the train from decelerating or stopping, ultimately causing the tragedy. This incident highlighted the impact of prolonged, high-intensity work on cognitive load in drivers. Fatigue significantly reduces the ability to handle multitasking, making it difficult for drivers to focus on critical operations and sharply diminishing their capacity to respond to emergencies. Additionally, the accident exposed shortcomings in South Korea’s traffic monitoring systems at the time, such as the lack of effective automated responses when drivers are distracted. The incident prompted South Korea to make significant improvements to railway safety systems, including the introduction of more advanced automatic braking and driver monitoring technologies to reduce the likelihood of similar incidents in the future.

 

In 2019, a multi-vehicle pile-up occurred on the Shin-Meishin Expressway in Japan due to a driver looking down to adjust the in-car navigation system while driving, failing to notice a sudden deceleration in traffic ahead. The driver’s distraction prevented timely braking, resulting in a collision with the vehicle in front and triggering a chain reaction involving multiple cars. The accident caused several injuries, prolonged highway closure, and significantly disrupted traffic. The investigation revealed that operating the in-car navigation system caused notable interference with the driver’s visual and manual attention allocation. During the few seconds, the driver looked down to check navigation information, their gaze was diverted from the road, missing critical signs of slowing traffic ahead. Simultaneously, manual operation of the navigation system occupied the driver’s control over the steering wheel and brakes, increasing the risk of an accident. This incident underscored the potential dangers of using in-car devices while driving. Japan has further promoted advanced driver-assistance systems, including collision warnings and automatic braking technology, and strengthened regulations against distracted driving behaviors to prevent similar accidents. Drivers are reminded to stay focused while driving to ensure road safety.

 

Based on the above, strategies to mitigate cognitive fatigue during driving include:

Regular breaks: Drivers should rest for 15 minutes after every 1–2 hours of driving. Resting reduces the metabolic burden on the frontal lobe and restores attention resources. Short breaks allow the brain’s default mode network to activate, facilitating information processing and integration. Activation of the default mode network helps improve attention recovery, enhances memory and creative associations, and alleviates neural fatigue.

 

Intermittent focus techniques: Using a method similar to the Pomodoro Technique, drivers can alternate between 25–30 minutes of focused driving and 5 minutes of relaxation to avoid frontal lobe overload.

Physical and sensory stimulation: Introducing moderate sensory changes during driving, such as playing rhythmic music or opening windows for fresh air, helps maintain alertness.

Assisted driving modes: When fatigue is detected, activating assistance systems can reduce risks.