- SWSD stands for shift work sleep disorder, a chronic condition related to the hours workers keep. People with this condition need to be extra careful when sleepy if they need to drive.
- Researchers at the University of Missouri looked through real-world data and discovered that people with SWSD are 300 percent more likely to be in a crash (or a “near crash”). Others with sleep troubles, like people with sleep apnea or insomnia, have a 30 percent greater risk.
- One of the study authors told Car and Driver that, if possible, it’s best to rest after work before getting behind the wheel or to rely on other drivers, like with public transportation or a taxi.
For centuries, people have been working through the night. But in the 21st century, people who work the “graveyard” shift—or any overnight job—may have to contend with an impact that people in the long-ago past did not: a much, much higher chance of crashing their car. Much higher.
Pretty much by definition, shift work sleep disorder (SWSD) commonly affects people who don’t work a traditional nine-to-five job and have to work through the night. According to the Cleveland Clinic, around 20 percent of the full-time workforce in the U.S. is required to do some sort of shift work, and of those people, 10 to 40 percent may suffer from the sleep disorder. On the low end, that means at least 2.5 million people are potentially affected with SWSD. The disorder “causes difficulties adjusting to a different sleep/wake schedule, which results in significant issues with falling asleep, staying asleep, and sleeping when desired,” the Clinic said on its website.
Researchers at the University of Missouri wanted to understand what happens to people’s ability to drive when their internal body clocks get turned around by SWSD. U of M Civil and environmental engineering professors Praveen Edara and Carlos Sun looked at data collected in a real-world driving study that was part of the second Strategic Highway Research Program, which was established by Congress and ran from 2006 to 2015. Their findings, in short, are that people with SWSD are three times more likely to crash (or be in a near crash) than people without this condition. Other sleeping problems, specifically sleep apnea or insomnia, resulted in a 30 percent greater chance of crashing (or nearly crashing).
“The magnitude of the crash risk increase for drowsy drivers is concerning, both to them and other motorists on the road,” Edara told Car and Driver. As the report noted, in 2017 the National Highway Traffic Safety Administration (NHTSA) recorded 91,000 “police-reported crashes” involving drowsy drivers, involving 50,000 injuries and close to 800 deaths.
It is still unclear exactly why SWSD was found to have a larger impact on safety than other sleep disruptions, he said, but there are some strategies night shift workers can take to minimize their risk of a crash. Unsurprisingly, these involve getting some rest or avoiding getting behind the wheel.
“Due to the heightened safety risk experienced by drivers with SWSD, late-shift workers are encouraged to use non-driving transportation modes, such as taxi, transportation network companies, and public transit, when available,” Edara said. “Resting before driving back to home after completing their shift is another option to mitigate the risk. This is consistent with the Hours of Service guidelines established for long-haul commercial drivers by the Federal Motor Carrier Safety Administration that include rest periods to increase driver alertness.”
The National Transportation Safety Board releases a list of its top 10 most wanted safety improvements each year. While the 2020–2021 list doesn’t include any mention of drowsy drivers, their 2019–2020 list includes “screening and treating obstructive sleep apnea” as well as “reduce fatigue-related accidents.”
Now that a link has been established between SWSD and an increased chance of crashing, Edara said in a statement that the next move should be to work with medical professionals to figure out exactly why the risk is higher in people with SWSD. Seems like there is an obvious answer here, but Edara said a better understand will help them “develop and test to improve the overall safety of these drivers and the other motorists around them.”
The study’s name is “Sleep Disorders and Risk of Traffic Crashes: A Naturalistic Driving Study Analysis,” and it was published in Safety Science.