Driver Fatigue and Mental Health

Understanding Driver Fatigue and Related Conditions

• Fatigue can be caused by various factors such as sleep deprivation, circadian rhythm disruptions, chronic sleep disorders, long and monotonous drives, medication, drugs, and shift schedules.
• A circadian rhythm is an internal process that regulates the sleep-wake cycle, repeating roughly every 24 hours, observed in animals, plants, fungi, and cyanobacteria.
• Certain groups, such as professional drivers, those with varying shift patterns, and individuals working long hours, are more susceptible to fatigue.
• Diagnosis of fatigue can be post-crash, pre-crash, or in a lab setting involving eye closure percentage, ocular parameters, heart rate variability, and neurological parameters.
• Fatigue-related legislation exists in some countries like the UK and Australia, involving the installation of equipment for recording vehicle use.
• Engineering solutions for road safety include considerations of driver visual attention, brain activity, mental workload, fatigue, and mental health.
• Attention Deficit Hyperactivity Disorder (ADHD) involves problems with concentration and impulse control in adults, with three sub-groups: predominantly hyperactive, predominantly with attention problems, and both symptoms.
• Drivers with ADHD have a higher risk of accidents, with a relative risk of 1.23, similar to drivers with cardiovascular diseases, and may also have comorbid conditions like Oppositional Defiant Disorder and Conduct Disorder.
• A meta-analysis debunked the long-standing belief that ADHD drivers have a fourfold risk of accidents, attributing the risk to comorbid conditions rather than ADHD itself.
• In a study, drivers with ADHD were associated with multiple collisions, while depression was linked to self-reported injury following a collision.
• ADHD symptoms were found to predict a 5% increased crash risk per increase in symptom severity score, corresponding to approximately 1 biennial crash and 1 annual near-crash per driver with ADHD.
• Crash and near-crash risks were also assessed in drivers with ADHD and depression, with ADHD symptoms showing an increased crash risk.

Driver Mental Workload and Fatigue

• There are three types of measures for indicating mental workload and driver state: performance, self-reporting, and psychophysiology.
• Lateral and longitudinal control reflect primary task performance in driving, with SDLP being sensitive to factors like alcohol use and fatigue.
• Self-reports, such as the Karolinska Sleepiness Scale, are useful for assessing driver state, but may not always be accurate due to timing and memory decay.
• Psychophysiological measures, like heart rate variability and EEG, are attractive indicators of mental workload or driver state, with some requiring more advanced equipment than others.
• Fatigue impairs cognitive and physical performance, and is reportedly one of the leading causes of crashes worldwide.
• Fatigue is a concept broader than sleepiness, and its physical manifestations are difficult to detect without invasive measures like EEG or pupillometry.
• One legal proxy for fatigue is the number of hours driven, but it is difficult to enforce in road transport and prove the link between lack of sleep and performance impairment.
• "Maggie’s law" in New Jersey facilitates the prosecution of fatigued drivers involved in crashes, based on scientific evidence that sleep deprivation has measurable effects on driver competence.
• Research has shown that being awake for 18 hours produces impairment equivalent to a blood alcohol concentration (BAC) of 0.05%, and at 24 hours, the equivalence is around 0.1%.
• The comparative effects of alcohol and prolonged wakefulness on driving performance show impairment levels equivalent to specific BAC levels at different test times.
• Driver mental workload and state can be assessed through performance, self-reports, and psychophysiological measures, reflecting factors such as lateral and longitudinal control, heart rate variability, and EEG activity.
• Fatigue impairs driving ability and is difficult to detect without invasive measures, leading to challenges in enforcement and prosecution, with "Maggie’s law" being a notable attempt to address this issue.