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Effectiveness: 2 Star Cost: Varies
Use: Low
Time: Long

Teens are less experienced at the task of driving, requiring more of their deliberate attention than is the case for experienced drivers (Lansdown, 2002). Several studies suggest that drivers 16 to 24 are somewhat more likely than other age groups to drive while drowsy (Royal, 2003; Wheaton et al., 2014). In a 2006 survey by the NSF (2006), 51% of 552 young drivers (grades 10 to 12) reported driving at least once while drowsy. One countermeasure that could reduce drowsy driving by teens is delaying high school start times.

Adolescents undergo a circadian cycle change known as “phase delay” whereby they experience sleepiness later in the evening and later wake times (Adolescent Sleep Working Group, Committee on Adolescence, & Council on School Health, 2014). The American Academy of Pediatrics recommends that teens get 8.5 to 9.5 hours of sleep per night. However, because of biological processes associated with changes in their circadian cycle in addition to societal factors such as homework and electronic device use, teens go to bed later, making it hard for them to get the full recommended hours of sleep. This leads to chronic sleep loss. In a 2014 policy statement, the American Academy of Pediatrics’ Adolescent Sleep Working Group recommended that one countermeasure to this problem is to delay high school start times.

In addition to improvements such as an increased attendance, improved grades, and less daytime sleepiness (Wheaton et al., 2016), research also shows that there is a reduction of teen driver motor vehicle crashes when high school start times are delayed. Danner and Phillips (2008) found that average crash rates for teen drivers in one school district in Kentucky were reduced by 16.5% after the delay in school start time. In a 2011 study done by Vorona et al., 16- to 18-year-olds in one Virginia county with later school start times were less likely to crash than in the neighboring county with earlier school start times. A 2019 study by Foss et al. also showed a decrease in crashes, albeit small, in 16- to 17-year-olds. Finally, a study looking at Fairfax County, Virginia, found a reduction in crashes in 16 to 18-year-old drivers when a 50-minute delay was implemented in high school start times (Bin-Hasan et al., 2020).


It is unclear how many school districts have or implemented later high school start times. In 2018, the National Center for Education Statistics (NCES) mapped out the average public high school start times throughout the United States. However, it is only a statewide average and does not distinguish the actual high school start times by district (NCES, 2020). Yip et al. (2022) did a meta-analysis and determined that the optimal high school start times were from 8:30 a.m. to 8:59 a.m. Only South Carolina (average start time of 8:34 a.m.) and the District of Columbia (average start time of 8:41 a.m.) fell within the optimal timeframe. In 2019 California mandated that high school begin no earlier than 8:30 a.m. as of July 2022.


Delayed high school start times are associated with some reduction in teen driver crashes. However, research completed to date could not determine whether a reduction in teen drowsiness is the main causal mechanism at work (Bin-Hassan et al., 2020; Foss et al., 2019). Further studies are needed to examine the causal relationship between teen drowsiness, crash reduction, and later high school start times.


The cost of changing school start times depends on a multitude of factors. The policy change itself is not expensive; it is the cascading effects of the change that may make later start times difficult to implement. Things that may make the change difficult to implement include changing bus schedules and routes, rescheduling after school activities, and other administrative costs. In the case of Fairfax County, Virginia, the projected cost was $5 million dollars (Rosenberg, 2015). However, in the case of Edina, Minnesota, they were able to make the changes that resulted in no “additional cost” according to the district superintendent at the time.

Time to Implement:

Much like cost, the implementation of changing high school start times would vary throughout the United States and may require policy change at either the local or State level. For example, in 2019 the State of California passed Pupil attendance: school start time, Senate Bill No. 328 stating, “The school day for high schools, including high schools operated as charter schools, shall begin no earlier than 8:30.” However, in other localities, the change came from the school district superintendent such as in the case of Edina. The time from conception to implementation varied. The California law was signed in October 2019 by the governor and came into effect in July 2022 (Pupil attendance), while in the case of Edina, it took 6 months (Rosenberg, 2015).