School Start Times, Sleep, Behavioral, Health, and Academic Outcomes: A Review of the Literature
Wheaton AG, Chapman DP, Croft JB · 2016
grade Dreviewindependentmixed
Sample
38 reports reviewed
Population
Adolescent students, mostly US
Design
Narrative literature review by CDC authors with no risk-of-bias assessment, no quality weighting, and no quantitative synthesis. It counts findings rather than grading them, which is exactly the failure mode the Cochrane review (Marx 2017) and the Biller 2022 systematic review were designed to correct. Widely cited in advocacy for later start times.
Key findings
Concludes that most studies show delaying school start times increases weeknight sleep duration among adolescents, primarily by delaying rise times, with significant increases even from delays of about half an hour, and that later start times "generally correspond to" improved attendance, less tardiness, less falling asleep in class, better grades, and fewer motor vehicle crashes. The sleep-duration conclusion is correct and is confirmed by better sources; the academic conclusion is not supported once the same literature is put through a risk-of-bias screen.
Genetic confound
Unaddressed. The review does not distinguish studies where start times were assigned by districts from studies comparing schools that differ for unmeasured reasons.
DOI / URL
Effects
| Outcome | Metric | Value | Measure | Timing | Vs | Horizon | Class |
|---|---|---|---|---|---|---|---|
| Weeknight sleep duration (health/behavioural) | narrative synthesis across 38 reports | most studies show increases, primarily via delayed rise times | mixed | varies | unclear | unclear | health |
| Grades, attendance, tardiness, motor vehicle crashes | narrative synthesis | "generally correspond to" improvement — no quality weighting applied | mixed | varies | unclear | unclear | domain-skill |