Table 2. Comparison of sample characteristics between primary and secondary school pupils.
| Measure (M (SD)) | Primary (n = 30) | Secondary (n = 31) | t/χ2 | p |
|---|---|---|---|---|
| Datasets excluded, N (% of sample with accelerometry) | 4 (11.76) | 4 (11.43) | 0.002 | 0.965 |
| Age*, M (SD) | 10.97 (0.18) | 12.39 (0.92) | 8.30 | <0.001 |
| Female*, N (%) | 17 (56.67) | 22 (70.97) | 1.43 | 0.490 |
| missing, N (%) | 1 (3.33) | 1 (3.23) | ||
| SIMD higher deprivation school, N (%) | 17 (56.67) | 7 (22.58) | 7.42 | 0.006 |
| Number valid weekdays | 8.27 (1.48) | 8.45 (1.34) | 0.51 | 0.611 |
| Number of valid weekend days | 3.60 (0.81) | 3.61 (0.88) | 0.06 | 0.953 |
| Number of nights | 12.73 (2.23) | 13.10 (1.85) | 0.69 | 0.490 |
| Wore accelerometer on dominant wrist, N (%) | 16 (53.33) | 18 (58.06) | 1.10 | 0.577 |
| missing, N (%) | 1 (3.33) | 0 (0) | ||
| Accelerometry-derived activity measures | ||||
| Activity (ENMO) during L5 | 3.03 (0.84) | 2.91 (0.73) | 0.59 | 0.556 |
| Activity (ENMO) during M10 | 76.00 (21.61) | 54.84 (12.37) | 4.71 | <0.001 |
| Accelerometry-derived sleep measures | ||||
| SPT-window duration (hours) | 8.81 (0.67) | 8.40 (0.71) | 2.36 | 0.021 |
| Sleep duration (hours) | 7.67 (0.73) | 7.32 (0.64) | 1.96 | 0.054 |
| Sleep efficiency | 0.87 (0.03) | 0.87 (0.04) | 0.19 | 0.854 |
| Sleep onset–weekdays | 22:23 (44.4) | 22:50 (53.8) | 2.20 | 0.032 |
| Sleep onset–weekends | 23:23 (67.2) | 23:36 (75.6) | 0.66 | 0.514 |
| Wake time–weekdays | 07:05 (39.4) | 07:00 (38.6) | 0.51 | 0.610 |
| Wake time—weekends | 08:17 (77.7) | 8:32 (68.3) | 0.80 | 0.425 |
| Meets recommended sleep duration, N (%) | 0 (0) | 1 (3.23) | 0.98 | 0.321 |
| SPT-window meets recommended sleep duration, N (%) | 11 (36.67) | 10 (32.36) | 0.13 | 0.717 |
| Accelerometry-derived circadian measures | ||||
| Relative amplitude | 0.92 (0.03) | 0.90 (0.03) | 3.17 | 0.002 |
| Social jetlag (hours) | 1.10 (0.91) | 1.14 (0.80) | 0.17 | 0.866 |
| Questionnaires | ||||
| Total Sleep Score | 35.47 (10.06) | 37.45 (8.22) | 0.85 | 0.402 |
| Falling Asleep & Reinitiating Sleep | 19.20 (6.74) | 21.35 (5.82) | 1.34 | 0.186 |
| Returning to Wakefulness | 5.57 (2.56) | 5.35 (2.27) | 0.34 | 0.733 |
| Going to Bed | 10.70 (3.60) | 10.74 (2.73) | 0.05 | 0.959 |
| Mood and Feelings score | 3.80 (4.45) | 5.35 (3.88) | 1.46 | 0.151 |
| Subjective sleep/circadian measures | ||||
| Subjective sleep onset–weekdays | 22.06 (45.6) | 22.09 (55.2) | 0.21 | 0.836 |
| Subjective wake time—weekdays | 07:05 (37.8) | 07:09 (31.2) | 0.42 | 0.677 |
| Subjective sleep onset–weekends | 23:41 (98.4) | 23:07 (76.8) | 1.52 | 0.135 |
| Subjective wake time—weekends | 09:27 (95.4) | 09.06 (76.1) | 0.96 | 0.341 |
| Subjective sleep duration–weekdays | 8.98 (1.12) | 9.00 (1.22) | 0.06 | 0.956 |
| Subjective sleep duration—weekends | 9.77 (1.96) | 9.98 (1.57) | 0.48 | 0.633 |
| Subjective social jetlag | 1.98 (1.16) | 1.46 (0.88) | 1.96 | 0.055 |
| Feedback questions | ||||
| Problems with questionnaires? N (%) | 1 (3.33) | 0 (0) | 1.05 | 0.591 |
| Problems with accelerometer? N (%) | 15 (50.00) | 17 (54.84) | 1.11 | 0.574 |
* Age and sex are estimated, see Participants and Procedure. Values reported in ‘Primary’ and ‘Secondary’ columns are mean (standard deviation) unless otherwise specified. For sleep onset and wake times, values are time in 24hr clock (SD in minutes). ENMO = Euclidian Norm Minus One; SPT = Sleep Period Time.