As the name suggests, SWSD is most common in people who have non-traditional working hours, such as: B. the shift from 11pm to 7am. Working through the night and sleeping during the day for a long period of time can result in a disorder where a person has difficulty falling asleep when expected or needed. The Bureau of Labor Statistics found that in 2017 and 2018, 16% of American workers were working off-schedule.

Existing studies have already shown that sleep disorders can lead to unsafe driving; Most of these studies weren’t based on real-world data, however, said co-author Praveen Edara, PhD, of the University of Missouri.

“In the past, researchers have mainly studied sleep disorders in a controlled environment with test tracks and driving simulators,” Edara said in a statement. “Our study goes one step further by using actual observed crash and near-crash data from approximately 2,000 events in six US states.”

The new study is based on the federal government’s second strategic road research program. Investigators collected data from 1,892 traffic incidents in 6 states using binary logistic regression models with random effects to estimate the accident risk associated with SWSD, as well as sleep apnea and insomnia. They then took into account confounding variables such as roadway and traffic characteristics in order to determine the contribution of sleep disorders to the risk of accidents.

SWSD led to the highest risk of crash (odds ratio [OR] = 2.96); the risk was particularly high for older drivers (over 65 years of age). Drivers with sleep apnea were 29% more likely to have an accident or near-crash, and those with insomnia were 33% more likely to have an accident or near-crash. The analysis also found that drivers with a sleep disorder are 29% more likely to be inattentive behind the wheel.

Edara said he hoped that by quantifying and publishing the risks associated with sleeping disorders and driving, he and his colleagues can draw the necessary research attention to the problem.

“We want to work with public health professionals and medical professionals who have expertise in sleep research to better understand why this is happening,” he said. “This also enables us to investigate what kind of countermeasures we can develop to test and improve the overall safety of these drivers and the other drivers in their vicinity.”

Edara said security improvements can come from several directions. On the one hand, improvements in the treatment of sleep disorders can eliminate the cause of the increased risk, but additional driving technologies such as warnings of drowsiness and even self-driving cars could reduce the risk. In addition, it has become easier for people to use ride-sharing apps and services that could help people with insomnia to avoid being behind the wheel entirely.


Bharadwaj N, Edara P, Sun C. Sleep disorders and the risk of traffic accidents: A naturalistic driving study analysis. Security science. 2021; 140: 105295. doi: 10.1016 / j.ssci.2021.105295