School start time and sleep in Canadian adolescents
Bibliographic record
Abstract
Insufficient sleep is a serious problem in adolescents and school start time is thought to be a key contributor. This study provided the first comprehensive assessment of school start times across Canada and examined whether school start times were associated with sleep duration and tiredness among adolescents. We collected information on school start times from 362 schools that participated in the 2013/2014 Health Behaviour in School-aged Children study. We calculated sleep duration from weekday bedtime and wake time reported by 29 635 students (aged 10-18 years). We classified weekday sleep as sufficient if it met national recommendations, and used data on self-reported tiredness at school in the morning. Random-effects regression models estimated the association of school start time with sleep duration, sleep sufficiency and tiredness. On average, schools started at 08:43 hours. Students slept an average of 8:36 h on weekdays and 69% met sleep duration recommendations, but 60% reported feeling tired in the morning. Every 10-min delay in school start time corresponded with 3.2 [95% confidence interval (CI): 2.0, 4.5] additional minutes of sleep, a 1.6% (95% CI: 0.5, 2.8) greater probability of sufficient sleep and a 2.1% (95% CI: 1.0, 3.2) smaller probability of feeling tired at school in the morning. Students from schools that started later slept longer, were more likely to meet sleep recommendations and were less likely to report feeling tired in the morning. The study adds weight to the mounting evidence that delaying school start time benefits adolescent sleep.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.004 |
| Meta-epidemiology (narrow) | 0.000 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.002 |
| Bibliometrics | 0.003 | 0.007 |
| Science and technology studies | 0.004 | 0.001 |
| Scholarly communication | 0.002 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".