Table 2.
Means (95% CIs) and differences for sleep outcome variables across years using descriptive analytical methods
| Difference | |||||
|---|---|---|---|---|---|
| Pre-change | Post-change | Follow-up | Post–Pre | Follow-up–Post | |
| Younger elementary school (Grades K-2) | |||||
| Bedtime* | |||||
| Weekday | 20:32 (20:31–20:34) |
20:21 (20:19–20:22) |
20:19 (20:17–20:20) |
–11 min | –2 min |
| Weekend | 21:10 (21:09–21:12) |
20:59 (20:57–21:01) |
20:56 (20:54–20:58) |
–11 min | –3 min |
| Wake time* | |||||
| Weekday | 7:04 (7:03– 7:06) |
6:42 (6:41–6:43) |
6:41 (6:40–6:43) |
–22 min | –1 min |
| Weekend | 7:42 (7:41–7:44) |
7:32 (7:30–7:34) |
7:28 (7:26–7:30) |
–10 min | –4 min |
| Duration* | |||||
| Weekday | 10.53 h (10.51–10.56) |
10.35 h (10.33–10.38) |
10.38 h (10.36–10.41) |
–11 min | +2 min |
| Weekend | 10.54 h (10.51–10.56) |
10.55 h (10.52–10.58) |
10.53 h (10.49–10.56) |
+ <1 min | –2 min |
| Weekend oversleep*,† | 0.2 min (–1.3 to 1.6) |
12.1 min (10.3–13.9) |
8.7 min (7.0–10.5) |
+11.9 min | –3.4 min |
| % sufficient sleep‡ | 98.6% | 98.2% | 98.7% | –0.4% | +0.5% |
| % poor sleep quality§ | 22.3% | 21.0% | 19.7% | –1.3% | –1.3% |
| % daytime sleepiness|| | 34.8% | 38.8% | 33.0% | +4.0% | –5.8% |
| Older elementary school (Grades 3–5) | |||||
| Bedtime* | |||||
| Weekday | 21:13 (21:11–21:14) |
21:01 (21:00–21:02) |
21:02 (21:01–21:03) |
–12 min | +1 min |
| Weekend | 22:21 (22:19–22:23) |
22:19 (22:17–22:21) |
22:20 (22:18–22:22) |
–2 min | +1 min |
| Wake time* | |||||
| Weekday | 7:05 (7:04–7:06) |
6:42 (6:41–6:43) |
6:42 (6:41–6:43) |
–23 min | No change |
| Weekend | 8:33 (8:31–8:35) |
8:33 (8:31–8:35) |
8:33 (8:31–8:35) |
No change | No change |
| Duration* | |||||
| Weekday | 9.87 h (9.85–9.90) |
9.69 h (9.67–9.72) |
9.67 h (9.64–9.69) |
–11 min | –1 min |
| Weekend | 10.19 h (10.16–10.23) |
10.23 h (10.19–10.26) |
10.22 h (10.18–10.25) |
+2 min | – <1 min |
| Weekend Oversleep*,† | 14 min (12–16) |
26 min (24–28) |
28 min (26–30) |
+12 min | +2 min |
| % Sufficient sleep‡ | 83.5% | 81.2% | 80.2% | –2.3% | –1.0% |
| % Poor sleep quality§ | 24.1% | 25.8% | 23.8% | +1.7% | –2.0% |
| % Daytime sleepiness|| | 22.4% | 26.5% | 25.8% | +4.1% | –0.7% |
| Middle school (Grades 6–8) | |||||
| Bedtime* | |||||
| Weekday | 21:49 (21:48–21:51) |
21:58 (21:56–21:59) |
21:59 (21:57–22:00) |
+9 min | +1 min |
| Weekend | 23:22 (23:20–23:24) |
23:32 (23:30–23:34) |
23:30 (23:28–23:32) |
+10 min | –2 min |
| Wake time* | |||||
| Weekday | 06:27 (06:26–06:28) |
07:04 (07:04–07:05) |
07:02 (07:02–07:03) |
+37 min | –2 min |
| Weekend | 09:12 (09:10–09:14) |
09:20 (09:18–09:22) |
09:16 (09:14–09:18) |
+8 min | –4 min |
| Duration* | |||||
| Weekday | 8.63 h (8.60–8.65) |
9.11 h (9.09–9.14) |
9.06 h (9.04–9.09) |
+29 min | –3 min |
| Weekend | 9.83 h (9.79–9.86) |
9.79 h (9.76–9.82) |
9.78 h (9.75–9.81) |
–2 min | – <1 min |
| Weekend oversleep*,† | 1.13 h (1.10–1.17) |
0.60 h (0.57–0.63) |
0.64 h (0.61–0.68) |
–32 min | +2 min |
| % Sufficient sleep‡ | 40.5% | 61.0% | 59.6% | +20.5% | –1.4% |
| % Poor sleep quality§ | 30.3% | 27.7% | 28.9% | –2.6% | +1.2% |
| % Daytime sleepiness|| | 48.7% | 37.1% | 38.5% | –11.6% | +1.4% |
| High school (Grades 9–12) | |||||
| Bedtime* | |||||
| Weekday | 22:23 (22:21–22:25) |
22:37 (22:36–22:39) |
22:46 (22:44–22:47) |
+14 min | +9 min |
| Weekend | 23:47 (23:45–23:50) |
00:02 (00:01–00:04) |
00:06 (00:05–00:08) |
+15 min | +4 min |
| Wake time* | |||||
| Weekday | 05:46 (05:45–05:47) |
06:46 (06:45–06:47) |
06:45 (06:44–06:46) |
+60 min | –1 min |
| Weekend | 09:16 (09:14–09:19) |
09:27 (09:25–09:29) |
09:27 (09:25–09:29) |
+11 min | No change |
| Duration* | |||||
| Weekday | 7.39 h (7.36–7.41) |
8.14 h (8.12–8.17) |
7.99 h (7.97–8.01) |
+45 min | –9 min |
| Weekend | 9.48 h (9.44–9.52) |
9.41 h (9.38–9.44) |
9.34 h (9.31–9.37) |
–4 min | –4 min |
| Weekend oversleep*,† | 2.05 h (2.01–2.09) | 1.21 h (1.18–1.24) |
1.28 h (1.25–1.31) |
–77 min | +4 min |
| % Sufficient sleep‡ | 30.4% | 62.7% | 57.6% | +32.3% | –5.1% |
| % Poor sleep quality§ | 43.1% | 31.2% | 35.3% | –11.9% | +4.1% |
| % Daytime sleepiness|| | 76.2% | 55.2% | 62.0% | –21.0% | +6.8% |
h = hours, min = minutes.
*Data are presented as mean (95% CI), with military time used for bedtimes and wake times.
†Weekend oversleep is the difference between weekday and weekend sleep duration.
‡Sufficient sleep defined as an average of at least 9 h for ES and MS, and at least 8 h for HS4.
§Poor sleep quality defined as T ≥ 60 on PROMIS Pediatric Sleep Disturbance items.
||Daytime sleepiness defined as T ≥ 60 on PROMIS Pediatric Sleep Related Impairment items.