To review and meta-analyze existing evidence regarding the impact of school start times (SSTs) on youth sleep and developmental outcomes considering the moderating effects of youth and school characteristics. Scopus, ScienceDirect, JSTOR, Pubmed, PsychInfo, ERIC, Proquest, EBSCO, and Google Scholar were used through 2019 to select studies measuring (1) school start time and (2) sleep or other developmental outcomes. Data from 28 studies and 1 774 509 participants were extracted and analyzed using random-effects models with robust variance estimation.
Later SSTs were associated with better overall developmental outcomes, longer sleep duration, and less negative mood. Specifically, new SSTs between 8:30 and 8:59 were associated with better outcomes than 8:00 to 8:29 start times. Later SSTs were more strongly associated with lower levels of sleepiness for high school (versus middle school) youth, and youth in private (versus public) schools reported better sleep and later wake times with later SSTs. Although this meta-analysis suggests an overall benefit of later SSTs, there was limited research to test outcomes such as sleep hygiene, naps, and behavioral and physical health outcomes.
There is converging evidence that later SSTs are associated with better overall developmental outcomes, longer sleep duration, and less negative mood. More research needs to consider student and school characteristics to obtain reliable estimates related to possible differences by sex, race, school size, percent free/reduced lunch, and percent minority.