Later school start times linked to fewer car crashes involving teens
Delaying school start times by slightly more than an hour led to fewer instances of teenagers driving while drowsy and fewer motor vehicle accidents involving younger drivers, researchers reported at SLEEP.
In the new study, Lisa J. Meltzer, PhD, CBSM, the director of the pediatric behavioral sleep and clinical actigraphy programs at National Jewish Health in Denver, led a team of researchers who analyzed the effect of delaying school start times by 70 minutes on drowsy driving and motor vehicle accidents among 2,100 high school students at a district in Arapahoe County, Colorado.
The students self-reported drowsy driving data, while a transportation agency provided information on the frequency and timing of weekday crashes involving drivers aged 16 to 18 years and adults who lived in the same county as the school district, as well as residents of four other counties in the metro Denver area.
The analysis showed that, overall, 29.3% of students reported driving while drowsy in the school year before the change in start time, compared with 20.3% of students in the school year when the time change was enforced and 23.7% in the school year after the time change. However, the students who said they had fewer than 8 hours of sleep reported driving while drowsy more frequently across this same timespan (P scores ranged from < .001 to < .037).
The motor vehicle accident rate in Arapahoe County dropped from 78.9 crashes for every 1,000 drivers in the school year before the change in start time to 76.6 crashes for every 1,000 drivers in the school year when the time change occurred and 68.7 crashes for every 1,000 drivers in the school year immediately after the time change.
Although crash rates did not differ between Arapahoe County and the other counties in the year before the change in start time, crash rates were significantly lower in Arapahoe County during the other two studied time periods (P scores chronologically = .048 and .046). In addition, there was no significant difference in morning crash rates per hour among all counties in the school year before the time change, but during the two other studied time periods, morning accident rates peaked an hour earlier in other counties vs. Arapahoe County. Motor vehicle accident rates involving adults in all the counties were consistent throughout the study.
“The results of our study not only support previous findings, but this is the first study to prospectively and concurrently examine sleep, drowsy driving and crash rates,” Meltzer said.
She added that the new findings are “very encouraging,” and demonstrate how certain policy changes can positively influence adolescent sleep, health and well‐being.
“Primary care providers should not only screen adolescent patients for insufficient sleep but should also support local school districts who are considering changing to healthy start times,” she said.