Table 3.
Sleep parameters mean value and night-to-night variability
| All (n=247) | Boys (n=103) | Girls (n=144) | p-valueb | |
|---|---|---|---|---|
| Sleep parameters | ||||
| Sleep/rest duration | ||||
| Total sleep time, h/night, mean (SD) | ||||
| All days | 6.6 (0.7) | 6.6 (0.7) | 6.6 (0.6) | 0.43 |
| School days | 6.2 (0.7) | 6.2 (0.8) | 6.2 (0.7) | 0.92 |
| Nonschool days | 7.3 (1.1)** | 7.2 (1.3)** | 7.4 (1.0)** | 0.19 |
| Total rest time, h/night, mean (SD) | ||||
| All days | 7.5 (0.7) | 7.5 (0.7) | 7.6 (0.7) | 0.60 |
| School days | 7.1 (0.8) | 7.1 (0.9) | 7.1 (0.8) | 0.95 |
| Nonschool days | 8.4 (1.3)** | 8.3 (1.5)** | 8.4 (1.1)** | 0.43 |
| Sleep quality | ||||
| Sleep efficiency, %, mean (SD) | ||||
| All days | 87.8 (4.2) | 87.6 (3.9) | 87.9 (4.5) | 0.58 |
| School days | 88.0 (4.5) | 88.0 (4.6) | 88.0 (4.5) | 0.92 |
| Nonschool days | 87.5 (4.8) | 86.9 (4.2)* | 87.9 (5.2) | 0.09 |
| Sleep onset latency, min, mean (SD) | ||||
| All days | 1.6 (0.8) | 1.6 (0.8) | 1.6 (0.7) | 0.83 |
| School days | 1.6 (1.0) | 1.6 (1.0) | 1.6 (1.0) | 0.91 |
| Nonschool days | 1.6 (1.2) | 1.6 (1.3) | 1.6 (1.2) | 0.98 |
| Number of awakenings, N, mean (SD) | ||||
| All days | 20.0 (5.6) | 20.0 (5.5) | 19.9 (5.7) | 0.92 |
| School days | 18.5 (5.6) | 18.2 (5.7) | 18.6 (5.4) | 0.56 |
| Nonschool days | 22.8 (8.0)** | 23.6 (8.3)** | 22.3 (7.8)** | 0.21 |
| Sleep timing | ||||
| Bedtime, o’clock, mean (SD (min)) | ||||
| All days | 00:46 (53) | 00:55 (51) | 00:40 (53) | 0.047 |
| School days | 00:20 (53) | 00:24 (55) | 00:17 (51) | 0.29 |
| Nonschool days | 01:40 (75)** | 02:00 (84)** | 01:26 (64)** | 0.0012 |
| Rise time, o’clock, mean (SD (min)) | ||||
| All days | 08:21 (43) | 08:30 (47) | 08:15 (40) | 0.008 |
| School days | 07:26 (36) | 07:31 (41) | 07:22 (31) | 0.08 |
| Nonschool days | 10:10 (82)** | 10:31 (85)** | 09:55 (76)** | 0.0005 |
| Night-to-night variability in sleep parametersa | ||||
| Total sleep time, min, mean (SD) | 75.8 (37.2) | 81.8 (44.5) | 71.6 (30.5) | 0.04 |
| Total rest time, min, mean (SD) | 85.6 (42.0) | 94.5 (48.6) | 79.2 (35.5) | 0.008 |
| Sleep efficiency, %, mean (SD) | 4.0 (1.6) | 4.3 (1.7) | 3.8 (1.6) | 0.02 |
| Sleep onset latency, min, mean (SD) | 1.7 (0.7) | 1.6 (0.6) | 1.7 (0.7) | 0.27 |
| Number of awakenings, N, mean (SD) | 6.2 (2.6) | 6.8 (2.8) | 5.6 (2.3) | 0.001 |
| Bedtime, min, mean (SD) | 67.7 (39.5) | 77.9 (52.0) | 60.4 (25.5) | 0.002 |
| Rise time, min, mean (SD) | 99.3 (40.4) | 107.4 (45.0) | 93.5 (35.8) | 0.01 |
Difference between school days and nonschool days is marked *p < 0.05 and **p < 0.0001.
SD = standard deviation; h = hours; min = minutes; n/N = number.
a
Across the entire week.
b
p-values for tests of between sex differences, significant values are bolded.