Table 2 Characteristics of adolescents with regard to sleep duration, bedtime, and pubertal timing
Characteristics, N (%) | Sleep duration X (SD)/N (%) | P | Bedtime X (SD)/N (%) | P | Pubertal timing X (SD)/N (%) | P | |||
|---|---|---|---|---|---|---|---|---|---|
Insufficient | Sufficient | ≤ 10 pm | > 10 pm | On time | Early | ||||
Sex | |||||||||
 Male, 2889 (52.9) | 438 (15.2) | 2451 (84.8) | 0.840 | 2253 (78.0) | 636 (22.0) | < 0.001 | 2223 (76.9) | 666 (23.1) | 0.948 |
 Female, 2572 (47.1) | 395 (15.4) | 2177 (84.6) | 1894 (73.6) | 678 (26.4) | 1981 (77.0) | 591 (23.0) | |||
Only child | |||||||||
 Yes, 1019 (18.7) | 163 (16.0) | 856 (84.0) | 0.465 | 749 (73.5) | 270 (26.5) | 0.044 | 750 (73.6) | 269 (26.4) | 0.004 |
 No, 4442 (81.3) | 670 (15.1) | 3772 (84.9) | 3398 (76.5) | 1044 (23.5) | 3454 (77.8) | 988 (22.2) | |||
Father’s education level | |||||||||
 Low, 3161 (57.9) | 545 (17.2) | 2616 (82.8) | < 0.001 | 2238 (70.8) | 923 (29.2) | < 0.001 | 2408 (76.2) | 753 (23.8) | 0.118 |
 Medium, 2108 (28.6) | 262 (12.4) | 1846 (87.6) | 1741 (82.6) | 367 (17.4) | 1653 (78.4) | 455 (21.6) | |||
 High, 192 (3.5) | 26 (13.5) | 166 (86.5) | 168 (87.5) | 24 (12.5) | 143 (74.5) | 49 (25.5) | |||
Mother’s education level | |||||||||
 Low, 3209 (58.8) | 558 (17.4) | 2651 (82.6) | < 0.001 | 2249 (70.1) | 960 (29.9) | < 0.001 | 2451 (76.4) | 758 (23.6) | 0.297 |
 Medium, 2084 (38.2) | 244 (11.7) | 1840 (88.3) | 1748 (83.9) | 336 (16.1) | 1627 (78.1) | 457 (21.9) | |||
 High, 168 (3.0) | 31 (18.5) | 137 (81.5) | 150 (89.3) | 18 (10.7) | 126 (75.0) | 42 (25.0) | |||
Economic status | |||||||||
 Poor, 719 (13.2) | 120 (16.7) | 599 (83.3) | < 0.001 | 525 (73.0) | 194 (27.0) | < 0.001 | 547 (76.1) | 172 (23.9) | 0.168 |
 Medium, 2760 (50.5) | 472 (17.1) | 2288 (82.9) | 1915 (69.4) | 845 (30.6) | 2103 (76.2) | 657 (23.8) | |||
 Good, 1982 (36.3) | 241 (12.2) | 1741 (87.8) | 1707 (86.1) | 275 (13.9) | 1554 (78.4) | 428 (21.6) | |||
Parents’ relationship | |||||||||
 Poor, 177 (3.2) | 38 (21.5) | 139 (78.5) | 0.033 | 125 (70.6) | 52 (29.4) | 0.004 | 138 (78.0) | 39 (22.0) | 0.195 |
 Neutral, 709 (13.0) | 117 (16.5) | 592 (83.5) | 509 (71.8) | 200 (28.2) | 527 (74.3) | 182 (25.7) | |||
 Harmonious, 4575 (83.8) | 678 (14.8) | 3897 (85.2) | 3513 (76.8) | 1066 (23.2) | 1539 (77.4) | 1036 (22.6) | |||
Parenting style | |||||||||
 Democratic, 3609 (66.1) | 567 (15.7) | 3042 (84.3) | 0.046 | 2717 (75.3) | 892 (24.7) | 0.014 | 2794 (77.4) | 815 (22.6) | 0.031 |
 Autocratic, 1012 (18.5) | 164 (16.2) | 848 (83.8) | 756 (74.7) | 256 (25.3) | 773 (76.4) | 239 (23.6) | |||
 Doting, 601 (11.0) | 70 (11.6) | 531 (88.4) | 486 (80.9) | 115 (19.1) | 471 (78.4) | 130 (21.6) | |||
 Disregardful, 239 (4.4) | 32 (13.4) | 207 (86.6) | 188 (78.7) | 51 (21.3) | 166 (69.5) | 73 (30.5) | |||
Age | 12.07 (1.74) | 11.30 (2.07) | < 0.001 | 10.83 (1.88) | 13.26 (1.33) | < 0.001 | 11.40 (2.06) | 11.47 (1.99) | 0.281 |
BMI | 18.90 (3.36) | 17.94 (3.27) | < 0.001 | 17.66 (3.30) | 19.43 (2.92) | < 0.001 | 17.94 (3.26) | 18.57 (3.39) | < 0.001 |