Commercial Truck Driver Fatigue: Statistics and Safety Risks

Every hours-of-service rule in federal law is a fatigue rule, and fatigue is the crash factor the national record measures worst. When federal investigators took apart nearly a thousand serious truck crashes in the early 2000s, they coded fatigue for 13 percent of the truck drivers¹. In the government’s census of fatal crashes for 2019 and 2020, police coded drivers of large trucks as asleep or fatigued 1.4 percent of the time²³. The two figures measure different things in different crashes. The distance between them is still the first thing anyone using fatigue data has to understand.

What fatigue does to a driver

Fatigue is less a single condition than three pressures that stack on top of one another.

Sleep debt. Lost sleep accumulates, and one long night does not clear it. NHTSA’s drowsy-driving guidance points adults to seven to eight hours of sleep a night⁴. A driver who starts a run short of that is carrying the deficit before the truck leaves the yard.

Circadian low points. The body’s internal clock produces two troughs in alertness every day. FMCSA advises commercial drivers to avoid driving, where they can, between midnight and 6 a.m. and between 2 p.m. and 4 p.m., when the body is naturally drowsy⁵. NHTSA reports that drowsy-driving crashes happen most often between midnight and 6 a.m. or in the late afternoon⁴. Freight schedules do not follow biology, and overnight runs put trucking work across the deepest trough.

Time on task. FMCSA’s guidance warns that drowsiness can deepen the longer a driver has been on the road, but it also reports that an FMCSA study found alertness was tied more closely to time of day than to time on task⁵. A rule that caps hours without regard to when they fall addresses only part of the problem.

All three end in the same place: the micro-sleep. NHTSA describes brief losses of consciousness lasting four or five seconds, and notes that at 55 miles per hour a vehicle covers more than 100 yards in that time⁴.

What the Large Truck Crash Causation Study found

The Large Truck Crash Causation Study (LTCCS), run by FMCSA and NHTSA, examined 967 crashes from 2001 to 2003 at 24 sites in 17 states. Each involved at least one large truck and at least one injury or death, and the sample was weighted to represent about 141,000 trucks nationally¹. Investigators interviewed drivers and witnesses, inspected the trucks and pulled carrier, police and medical records.

Fatigue was coded as an associated factor for 13.0 percent of the trucks. An associated factor is any of roughly 1,000 conditions recorded as present at the time of the crash. The code says the condition existed, not that it contributed. FMCSA’s report is blunt on the point: “None of these variables in and of themselves should be considered the cause of the crash”¹. A fatigued trucker who is struck from behind at a red light still has fatigue on the form.

Two related codes sit in the same table. Drivers were coded as under work-related pressure in 9.2 percent of cases, and as pressured to operate even though fatigued in 3.2 percent¹.

The study’s analysis brief asked a sharper question. For each factor it calculated a relative risk: how often trucks with the factor were assigned the “critical reason” for the crash, the immediate failure that made the collision unavoidable, compared with trucks without it. That is a research classification, not a finding of fault. For fatigue, the relative risk was 8.0⁶. When fatigue was coded, the truck was eight times as likely to be the vehicle assigned the “critical reason”.

A fatigued trucker who is struck from behind at a red light still has fatigue on the form.

The study also cuts against the picture of the tired trucker as the whole story. In two-vehicle crashes between a large truck and a passenger vehicle, fatigue was coded for about 7.5 percent of truck drivers and 14.7 percent of passenger vehicle drivers, roughly twice as often for the person in the car¹.

Why police crash data undercount fatigue

FARS, NHTSA’s census of fatal crashes, records driver-related factors from police reports. Among drivers of large trucks in fatal crashes, 71 of 4,949 were coded as asleep or fatigued in 2019, and 68 of 4,777 in 2020²³. That is 1.4 percent in each year.

The FARS and LTCCS figures cannot be read as a trend. One is a census of fatal crashes built from police reports. The other was a weighted sample of injury and fatal crashes worked by trained investigators two decades earlier. The gap still points where NHTSA itself points. The agency says a precise count of drowsy-driving crashes “is not yet possible,” that its figures rely on police and hospital reports, and that there is broad agreement those figures are an underestimate⁴. Across all vehicle types, NHTSA reports 644 deaths in drowsy-driving crashes in 2024⁴.

The reasons are practical:

• There is no roadside test for fatigue, nothing like a breath test for alcohol.
• The driver may be dead, badly hurt, or unwilling to say how long he or she had been awake.
• An officer sees the result (no braking before impact, a slow drift across a lane) but not the state of the person at the wheel.
• The evidence that would support the code, such as hours on duty in the days before, sits in records the officer does not have at the scene.

In 2019, 4.0 percent of large-truck drivers in single-vehicle fatal crashes were coded asleep or fatigued, against 0.8 percent in multiple-vehicle crashes². One plausible reading is that fatigue is easier to identify when no other driver’s actions compete for the explanation. Either way, treat police-coded fatigue as a floor. Our field guide to U.S. crash data covers how these datasets are built.

Sleep apnea and the medical certificate

Obstructive sleep apnea is a disorder in which the upper airway repeatedly narrows or closes during sleep, interrupting breathing and breaking up sleep, often without the sleeper knowing. The result can be heavy daytime sleepiness in someone who believes he or she slept a full night. [Verified statistic and source required: estimated prevalence of moderate-to-severe obstructive sleep apnea among U.S. commercial motor vehicle drivers, from FMCSA Medical Review Board materials or a peer-reviewed study]

Interstate commercial drivers must generally pass a physical given by a medical examiner listed on FMCSA’s National Registry of Certified Medical Examiners and be re-examined at least every 24 months (49 CFR 391.43 and 391.45)⁷. The physical standard that covers apnea is a general one. Section 391.41(b)(5) disqualifies a driver with a respiratory dysfunction likely to interfere with the ability to control the vehicle safely. The regulation does not mention sleep apnea.

Rulemaking to change that started and stopped. In March 2016, FMCSA and the Federal Railroad Administration published an advance notice of proposed rulemaking on moderate-to-severe obstructive sleep apnea among drivers and rail workers in safety-sensitive jobs. In August 2017 the agencies withdrew it, saying current safety programs and FRA’s fatigue risk management rulemaking were the appropriate ways to address the issue⁸⁹.

What remains is guidance. FMCSA’s Medical Examiner’s Handbook, issued in final form in January 2024, states that the regulations do not require examiners to screen drivers for sleep apnea or to refer them for testing, and FMCSA says it “has not adopted requirements regarding OSA screening, testing, or treatment”¹⁰. The handbook leaves the call to the examiner. Whether a driver with untreated apnea is identified depends heavily on who performs the exam.

Schedule pressure, detention and parking

Fatigue is also an operations problem. Under 49 CFR 395.2, on-duty time includes time spent at a shipper’s property waiting to be dispatched and time attending a truck while it is loaded or unloaded¹¹. For property carriers, the 14-hour window keeps running through all of it, and the next appointment rarely moves to match. Our explainer on hours-of-service rules walks through how the clocks interact on a day like that.

The Department of Transportation’s Office of Inspector General put a number on the risk in 2018. Using 2013 data, it found that “a 15-minute increase in average dwell time increases expected average crash rates by 6.2 percent,” and estimated that detention was associated with $1.1 billion to $1.3 billion a year in lost earnings for truckload drivers¹². The same report said accurate industrywide detention data do not exist.

Then comes the question of where to sleep. Jason’s Law is named for Jason Rivenburg, a truck driver who in March 2009 arrived near a South Carolina delivery before the receiver was open, parked at an abandoned gas station, and was attacked and murdered while he slept¹³. The law, enacted as part of MAP-21, required a survey of whether each state could offer adequate truck parking. FHWA’s 2015 results documented more than 300,000 truck parking spaces. More than 75 percent of truck drivers reported regularly having problems finding safe parking when they needed rest, 90 percent reported struggling at night, and almost half of state transportation departments reported unofficial or illegal truck parking on freeway ramps and shoulders¹⁴.

The shortage turns directly into fatigue risk. A driver who knows the lots fill by evening can stop early to claim a space, giving up hours and pay, or push on toward a distant lot and arrive tired.

What the records show, and what they miss

No device measures fatigue. The hours-of-service record is the nearest proxy: when the driver came on duty, how long he or she drove, and when breaks and sleeper-berth periods fell. Bills of lading and dispatch records can show where detention ate the day. None of it shows whether off-duty time was spent asleep. Our brief on what an electronic logging device records sets out what that data contains, and our analysis of the leading causes of large truck crashes places fatigue alongside the other factors the federal study coded.

For a carrier reviewing a crash, the useful question is not only whether the driver was within the rules. It is what the days before looked like: when the driver slept, where the truck sat overnight, and how long the last stop really took.