"Drivers who have slept for two hours or less in the preceding 24 hours are not fit to operate a motor vehicle." - Expert Consensus Statement on Drowsy Driving
Traffic safety experts estimate that sleepiness is associated with 21% of all motor vehicle crashes in which a person was killed and 13% of those requiring hospitalization which result in 328,000 police-reported crashes, 109,000 injuries, and 6,400 deaths in the Unites States each year. In 2021, the most recent year for which data is available, the number of fatalities involving drowsy drivers was 684 or 1.6 percent of total fatalities. This represents an 8.2-percent increase from 632 in 2020 (2).
A survey of long-haul truck drivers reported that 65% of drivers reported symptoms of drowsiness such as yawning, feeling drowsy or sleepy, and struggling to stay alert while driving and 3% of drivers reported actually falling asleep at the wheel. Interestingly, a survey of truck drivers conducted by the American Transportation Research Institute found that 66% of drivers indicated increased fatigue while driving as a direct result of the Hours of Service (HOS) rules that became effective in July 2013. HOS regulations were revised again in 2020 and provide exceptions and modifications that allow drivers to be on the road for longer periods of time.
What is Fatigue?
The trucking industry uses the term “fatigue” to describe the feeling of being tired (either mentally or physically). However, scientists use the term “fatigue” in reference to sleep deprivation or drowsiness. Sleep deprivation can generally be defined as the condition of not having enough sleep to function properly.
There are two types of sleep deprivation—acute and chronic. Acute sleep deprivation refers to no sleep or inadequate sleep over a short period of time (usually 1 to 2 days). Chronic sleep deprivation refers to regularly getting insufficient sleep for optimal performance where the sleep loss adds up over time as does the performance decrements associated with lack of adequate sleep.
How Much Sleep is Needed?
- The National Institutes of Health recommend that adults get 7-9 hours of sleep per night in order to maintain physical health and to ensure proper functioning throughout the day including staying awake at school, work, and while driving.
- Drivers who only sleep 4-5 hours per night are 2x more likely to cause a crash than drivers who got 7 or more hours of sleep. Drivers who get less than 4 hours of sleep are 11x more likely to cause a crash.
Effects of Fatigue
- Falling asleep while driving
- Microsleeps
- Increased reaction time
- Degraded attention and vigilance
- Increased distractibility and confusion
- Decreased motivation
- Increased probability of driving performance errors
Fatigue Imitates Alcohol
- 24 hours of continuous wakefulness impairs neurobehavioral performance in a manner similar to that induced by a blood alcohol concentration of 0.10 g/dL, which is beyond the legal limit in all 50 US states.
- 17-19 hours of continuous wakefulness is equivalent to a BAC of .05 g/dL.
Build a Strong Drowsy Driving Case
Our team brings deep expertise in human factors, commercial trucking compliance, and accident analysis. Whether the case involves a fatigued commercial driver or a private motorist, we provide the technical, behavioral, and regulatory insights needed to uncover the role fatigue played in the crash. Let Evidence Solutions support your case with detailed analysis from industry-leading specialists.