Table 1.
Characteristics of the Studies and Summary of Findings
| Study and country | Setting and participants | Design | Intervention Condition and period (exposure) | Control condition | Measure type and follow-up points | Findings | |||
|---|---|---|---|---|---|---|---|---|---|
| Timing | Efficiency | Duration | Hygiene | ||||||
| Baldursdottir et al. (2017) [38] Iceland |
Four first-year classes from four upper-secondary schools Int: n = 26, 15–16 years, 56% female Con: n = 27, 15–16 years, 65% female |
CRT | Physical activity 3 weeks (-) |
No tracking of steps nor text messages during the intervention period. | Self-report 3 weeks |
✓/NS | |||
| Bavarian et al. (2016) [39] United States |
Fourteen kindergarten-to-grade-six and kindergarten-to-grade-eight schools Int: n = 295, M = 8.3 years (SD = 0.58), 53% female Con: n = 299, M = 8.3 years (SD = 0.55), 55% female |
CRT | Personal development 6 years (-) |
School as usual | Self-report 6 years |
NS | |||
| Beijamini & Louzada (2012) [58] Brazil |
Two classes in 1 school Int: n = 10, 13–14 years old, 70% female Con: n = 11, 13–14 years old, 36% female |
CRT | Sleep education 4 days (200 min) |
Classes as usual | Actigraphy 5 days |
NS | NS | NS | |
| Bonnar et al. (2015) [40] Australia |
Two year 11 classes from each of six high schools n = 193, M = 16.3 ± 0.4 years, 79% female |
CRT | Sleep education and bright light therapy 4 weeks (-) |
Classes as usual | Self-report 5 weeks, 11 weeks |
NS | ✓/NS | ✓ | |
| Cain et al. (2011) [41] Australia |
Two year 11 classes from each of three high schools n = 104 (intervention = 53, control = 51), M = 16.2 ± 0.4 years, 60% female |
CRT | Sleep education 4 weeks (200 min) |
Classes as usual | Self-report 6 weeks, 12 weeks |
NS | NS | NS | |
| Das-Friebel et al. (2019) [42] Switzerland |
Thirty-four seventh- to twelfth-grade classes from seven schools Int: n = 192, M = 15.0 years (SD = 1.71), 43% female Con: n = 160, M = 15.3 years (SD = 1.56), 50% female |
CRT | Sleep education 25 min (25 min) |
Placebo control | Self-report 4 weeks |
NS | ✓/NS | ||
| Inhulsen et al. (2022) [43] The Netherlands |
Fifty-nine second- and third-grade classes from 10 high schools Int: n = 605, M = 13.4 years (SD = 0.76), 59% female Con: n = 367, M = 13.2 years (SD = 0.64), 47% female |
CRT | Sleep education 1.5 weeks (135 min) |
Wait-list control | Self-report 1.5 weeks, 3 months |
×/NS | NS | ||
| John et al. (2016) [44] India |
Sixth to twelfth grades from two schools Int: n = 34, 53% female, [M = 14 years (SD = 2.15) across intervention and control] Con: n = 24, 46% female |
CRT | Stress management and sleep education 2 weeks (117.5 min) |
School as usual | Self-report 14 days, 6 weeks |
NR | NS | ||
| John et al. (2017) [45] India |
Sixth to twelfth grades from 6 schools n = 660, M = 13.6 years (SD = 1.70), 50% female |
CRT | Stress management and sleep education 2 weeks (112.5 min) |
Wait-list control | Self-report 2 weeks, 6 weeks |
NR | NR | NR | |
| Kira et al. (2014) [46] and Blunden et al. (2012) [59] New Zealand |
Two classes (year 9 and year 11/12) from 1 high school Int: n = 15, M = 14.8 years (SD = 1.1), 47% female Con: n = 14, M = 14.7 years (SD = 1.2), 43% female |
RCT | Sleep education 5 weeks (200 min) |
Wait-list control (condensed version of the intervention) | Self-report 5 weeks, 10 weeks |
✓/NS | ✓/NS | NS | |
| Lin et al. (2018) [47] Iran |
Two classes from each of 48 schools Int: n = 1425, M = 15.5 years (SD = 1.08), 55% female Con: n = 1416, M = 15.12 years (SD = 1.50), 52% female |
CRT | Sleep education 2 months (300 min) |
Wait-list control | Self-report 3 months, 8 months |
✓/NS | |||
| Lufi et al. (2011) [48] Israel |
Eighth grade from one school n = 47, M = 13.8 years (SD = 0.28), 57% female |
CRT | School start times 1 week (-) |
Regular school starting time | Actigraphy 1 week, 2 weeks |
✓/NS | NS | ✓ | |
| Moseley et al. (2009) [49] Australia |
Two year 11 psychology classes from each of two secondary schools n = 81, M = 15.6 years (SD = 0.60), 67% female |
CRT | Health education 4 weeks (200 min) |
Classes as usual | Self-report 4 weeks, 6 weeks |
NS | NS | ||
| Rigney et al. (2015) [50] Australia |
Year 6/7 classes from 12 junior schools (each school provided ≥ 1 class) n = 296, M = 12.2 years (SD = 0.60), 59% female |
CRT | Sleep education 4 weeks (200 min) |
Classes as usual | Actigraphy, self-report 6 weeks, 18 weeks |
✓/NS | NS | ✓/NS | NS |
| Sousa et al. (2013) [51] Brazil |
Twelfth grade from one school n = 34, M = 16.8 years (SD = 0.60), 84% female |
RCT | Sleep education 5 days (225 min) |
Classes as usual | Self-report 3 weeks |
NR | NR | ||
| Tamura & Tanaka (2014) [52] Japan |
Two classes (years 4, 5, and 6) from each of 2 elementary schools Int: n = 72, ages not reported, 44% female Con: n = 76, ages not reported, 49% female |
CRT | Sleep education 45min (45 min) |
Classes as usual | Self-report 2 weeks |
✓/NS | ✓/NS | NR | |
| Tamura & Tanaka (2016) [53] Japan |
Eight seventh grade classes from 5 junior high schools Int: n = 122, aged 12-13 years, 42% female Con: n = 121, aged 12-13 years, 58% female |
CRT | Sleep education 50 min (50 min) |
Wait-list control | Self-report 2 weeks |
✓/NS | ✓/NR | ✓ | ✓ |
| Uhlig et al. (2019) [54] The Netherlands |
Five eighth grade classes in a primary school Int: n = 52, M = 10.1 years (SD = 1.23), % female not reported Con: n = 23, M = 10.4 years (SD = 0.78), % female not reported |
CRT | Music education 4 months (720 min) |
Wait-list control | Actigraphy 4 months |
NS | ✓ | ||
| van Rijn et al. (2020) [55] Singapore |
Twelve eighth grade classes in a secondary school Int: n = 102, M = 14.0 years (SD = 0.37), 0% female Con: n = 108, M = 14.0 years (SD = 0.27), 0% female |
CRT | Sleep education 5 weeks (240 min) |
Placebo control | Actigraphy 6 weeks, 11 weeks |
NS | ✓/NS | NS | |
| Wing et al. (2015) [57] Hong Kong |
Seventh to eleventh grades from 14 secondary schools Int: n = 1545, M = 14.9 years (SD = 0.11), 70% female Con: n = 2168, M = 14.6 years (SD = 0.18), 52% female |
CRT | Sleep education ~3 months (80 min) |
School as usual | Self-report ~4 months |
✓/NS | ✓/NS | NS/NR | |
| Wolfson et al. (2015) [56] United States |
Twelve seventh grade classes in 2 middle schools Int: n = 70, M = 12.5 years (SD = 0.56), 60% female Con: n = 73, M = 12.6 years (SD = 0.48), 59% female |
CRT | Sleep education 4 weeks (320 min) |
Placebo control | Self-report ~5 weeks, ~10-11 months, ~15-16 months |
✓/NS | ✓/NS | ✓/NS | |
CRT, cluster-randomized trial; RCT, parallel randomized controlled trial. Timing, the location of sleep within a 24-hour period (variables include consistent/typical bedtime, lights-out time, sleep onset/offset times, wake-up time). Efficiency, the proportion of time asleep of the time dedicated for sleep (variables include sleep efficiency, sleep onset latency, nightly awakenings, sleep episode length, snooze time). Duration, the amount of time asleep within a 24-hour period (variables include sleep duration, total sleep time, 24-hour sleep, time in bed, and discrepancy between school day and weekend out-of-bed times). Hygiene, behaviors and environmental factors that promote sleep (variables include sleep hygiene, caffeine consumption, alcohol consumption, bedtime routine, and bedtime electronic media use). ✓, significant effects favoring intervention condition. ×, significant effects favoring control condition. NS, no significant difference between conditions. NR, not reported. ✓/NS, NS/NR, and ×/NS, multiple results with inconsistent outcomes (e.g. a significant effect at an initial follow-up point, but a null result at a subsequent follow-up point).