Examining the impact of later high school start times on the health and academic performance of high school students: a multi-site study

Collecting together the results of a three-year research study conducted with over 9,000 pupils in eight public high schools in US three states, this research project found that high schools that began teaching at 8:30am or later allowed more than 60% of pupils to obtain at least eight hours of sleep per school night.

The authors found that pupils’ academic outcomes – including grades earned in core subject areas of math, English, science and social studies, plus performance on state and national achievement tests – were significantly improved by start times of 8:35am or later. Later start time were also credited with better attendance rates and reduced tardiness.

Conversely, the authors found that earlier start times and getting less than eight hours of sleep had negative welfare effects on teenagers, with those getting less sleep reporting significantly higher depression symptoms, greater use of caffeine, and a greater risk for making poor choices around substance use. Finally, the number of car crashes for teen drivers from 16 to 18 years of age was significantly reduced by 70% when a school shifted start times from 7:35am to 8:55am.