They’re on our highways and our state roads.

We see them at rest stops and service plazas.

They move our economy. Literally.

They’re tractor-trailer trucks, and they’re a vital part of the U.S. economy, hauling 70% of consumer and industrial goods and logging about 200 billion miles annually in the United States.

Trucks, and the men and women who drive them, play an indispensable role in U.S. society.

But truck driving is a high-stress, high-risk profession.

Long-haul truck drivers work irregular hours under protracted and repeated stretches of continuous effort that can be exacerbated by road construction, traffic conditions, and changes in weather. For most, finding safe and suitable parking while on the road is a constant challenge.

Many drivers deal with elevated stress levels and fatigue, and they have limited opportunities for physical activity and limited access to fresh, healthy foods.

And moreover, life on the road is extremely isolating and lonely, with drivers often spending days or weeks away from home at a time, while coping with the constant pressure to log as many miles as they can, in order to earn as much money as possible, in an industry that has experienced significant consolidation in recent years.

The impact of those occupational conditions – especially the risks that long-haul truck drivers face of developing multiple adverse health conditions due to the conditions they face on-the-job – recently caught the attention of Merrill Singer, a professor emeritus in the Department of Anthropology at UConn.

“I began to read the literature on long-haul truck drivers, and the multiplicity of diseases that their jobs put them at special risk for, and how the political economy of truck driving is organized and controlled has increased the pressure on truck drivers – over time, it’s made their life more stressful,” says Singer. “And I started to explore the concept of occupational syndemics and how it related to the kinds of jobs that put people at heightened vulnerability.”

A medical anthropologist who researches and explores the relationships between culture, health, and disease, Singer developed the public health concept of syndemics, which refers to the clustering of diseases in certain populations and the biological interaction of multiple comorbid diseases in populations.

“Syndemics involves two or more diseases interacting and some set of social conditions that interact with those diseases and make people vulnerable, which then makes these diseases more harmful,” Singer explains.

In recent years, Singer has been examining how syndemics can be used to assess the ways that living and working conditions can promote disease clustering and further the adverse interactions of comorbid diseases and other health factors.

He looked at other high-risk occupation populations – including gold and coal mineworkers in South Africa and commercial fishermen – before turning his syndemics lens to long-haul truck drivers. He published his syndemic analysis on the biosocial health of long-haul truck drivers in the February 2025 edition of the Journal of Transport & Health.

In his analysis, Singer notes studies that found that long-haul truck drivers frequently experienced elevated cortisol levels and are often subject to problems with sleep, including inadequate sleep, insomnia, and disrupted sleep linked to obstructive sleep apnea. Reduced sleep duration has been linked to fatigue, drowsiness, job performance lapses, slowed reaction time, and impaired driving ability.

Long-haul truck drivers are also more likely to be cigarette smokers, to engage in binge drinking, and to use other substances. They often struggle with mental health disorders or chronic stress.

Because of their working conditions, they typically eat while driving or dine at truck stops and fast-food outlets, factors that limit their available food choices. The occupation is highly sedentary as well – few rest stops offer any sort of exercise equipment, and opportunities for physical activity while on the road are infrequent.

More than half of long-haul truck drivers report living with one or more health problems, while 80% report at least one serious health condition, including obesity, hypertension and cardiovascular disease, and diabetes and metabolic disorders.

Getting regular medical care to help treat these conditions is also a struggle, as there aren’t medical providers on the road and drivers always face pressure to cover more miles.

“A grave consequence of syndemics of the road,” Singer writes in his paper, “is family disruption and divorce, high turnover rate (employer hopping), a national shortage of drivers, a high and untreated disease burden, shortened lifespan, heightened rates of suicide, increased medical costs, and injurious and deadly highway crashes.”

The challenges faced by long-haul truck drivers only intensified during the COVID-19 pandemic.

Workers in the transportation/logistics sector have one of the highest per-capita excess mortality rates due to the COVID-19 virus, Singer notes. He recommends multipronged and multilayered syndemic interventions to help address the structural factors that place economically crucial long-haul truck drivers in the U.S. at risk.

“In the case of [long-haul truck drivers],” he wrote, “this would involve advocacy for public policy changes, as part of state and federal infrastructure planning, that address an array of health, social, environmental, and economic challenges…[c]oupled with this kind of advocacy, there is a need for  funding to support direct structured health interventions for drivers that simultaneously address multiple health issues in this population.”

In the current public health climate, where officials are closely monitoring the spread of bird flu into other mammals – including humans – policymakers and industry officials would be especially wise to consider the syndemics of the road, Singer says.

“Once an infectious agent transitions from whatever its original host was to mammals, it makes it much easier to make the next transition into other mammals, which it’s already started to do,” Singer says.

“If bird flu begins to spread directly human-to-human, it’s interaction with all of what else is going around, and in people with other preexisting conditions – diabetes, cancer, tuberculosis, et cetera – has the potential for another massive pandemic.”