Darien, Illinois – Teenage drivers who start school earlier in the morning show increased rates of car crashes versus those who start school later, according to a new study published in the Journal of Clinical Sleep Medicine.

The research looked at 16- to 18-year-old drivers in Virginia Beach, Virginia, where high school classes begin at 7:20 to 7:25 a.m., and in adjacent Chesapeake, Virginia, where classes start at 8:40 to 8:45. The researchers used data from 2008.

There were 65.8 automobile crashes for every 1,000 teenage drivers in Virginia Beach, versus 46.6 crashes per 1,000 in Chesapeake. Similar results were found for 2007, where students attending earlier classes had a crash rate that was 25 per cent higher, with 80.0 crashes versus 64.0 per 1,000 drivers. An investigation of traffic congestion in both cities did not reveal differences that could have accounted for the crash findings.

“We were concerned that Virginia Beach teens might be sleep-restricted due to their early rise times, and that this could eventuate in an increased crash rate,” said Dr. Robert Vorona, lead author of the study. “The study supported our hypothesis, but it is important to note that this study does not prove cause and effect. We are planning to perform subsequent studies to follow up on these results and to investigate other potential ramifications of early high school start times.”

According to the American Academy of Sleep Medicine, the average teenager needs a little more than nine hours of sleep each night, but chronic sleep restriction is a common problem among teenagers. During adolescence, a biological change shifts the typical onset of sleepiness to later at night. This delay can make it challenging for teenagers to get enough sleep when they have to wake up early for school.

Vorona said that starting high school later in the morning may promote driver alertness by allowing teenagers to get more sleep at night.

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