Table 1 Characteristics of respondents (N = 1227)
|  | Overall (n = 1227) | Male (n = 594) | Female (n = 633) | P value |
|---|---|---|---|---|
Grade | N (%) | Â | Â | 0.133 |
 1 | 288 (23.47) | 121 (20.37) | 167 (26.38) |  |
 2 | 75 (6.11) | 39 (6.57) | 36 (5.69) |  |
 3 | 91 (7.42) | 43 (7.24) | 48 (7.58) |  |
 4 | 676 (55.09) | 345 (58.08) | 331 (52.29) |  |
 5 | 97 (7.91) | 46 (7.74) | 51 (8.06) |  |
Major | Â | Â | Â | 0.263 |
 Medicine | 1087 (88.59) | 520 (87.54) | 567 (89.57) |  |
 Other | 140 (11.41) | 74 (12.46) | 66 (10.43) |  |
Ethnicity | Â | Â | Â | 0.873 |
 Han | 1193 (97.23) | 578 (97.31) | 615 (97.16) |  |
 Minority | 24 (1.96) | 16 (2.69) | 18 (2.84) |  |
Only child | Â | Â | Â | <0.001 |
 No | 740 (60.31) | 314 (52.86) | 426 (67.30) |  |
 Yes | 487 (36.69) | 280 (47.14) | 207 (32.70) |  |
Birthplace | Â | Â | Â | 0.225 |
 Urban | 432 (35.21) | 199 (33.50) | 233 (36.81) |  |
 Rural | 795 (64.79) | 395 (66.50) | 400 (63.19) |  |
Closet relationship | Â | Â | Â | 0.192 |
 Parents | 1006 (81.99) | 492 (82.83) | 514 (81.20) |  |
 Grandparents | 145 (11.82) | 60 (10.10) | 85 (13.43) |  |
 Siblings | 51 (4.16) | 27 (4.55) | 24 (3.79) |  |
 Other | 25 (2.04) | 15 (2.53) | 10 (1.58) |  |
Education of closest relationship | Â | Â | Â | 0.001 |
 Less than lower secondary education | 640 (52.16) | 301 (50.67) | 339 (52.97) |  |
 Upper secondary & vocational | 251 (20.46) | 148 (24.92) | 103 (16.27) |  |
 Tertiary education | 336 (27.38) | 145 (24.41) | 191 (30.17) |  |
Education of father | Â | Â | Â | 0.011 |
 Less than lower secondary education | 662 (53.95) | 313 (52.69) | 349 (55.13) |  |
 Upper secondary & vocational | 290 (23.63) | 157 (26.43) | 133 (21.10) |  |
 Tertiary education | 275 (22.41) | 124 (20.88) | 151 (23.85) |  |
Education of mother | Â | Â | Â | 0.010 |
 Less than lower secondary education | 820 (66.83) | 386 (64.98) | 434 (68.56) |  |
 Upper secondary & vocational | 235 (19.15) | 136 (22.90) | 99 (15.64) |  |
 Tertiary education | 172 (14.02) | 72 (12.12) | 100 (15.80) |  |
Job of closest relationship | Â | Â | Â | 0.003 |
 Workers | 396 (32.27) | 226 (38.05) | 170 (26.86) |  |
 Farmers | 206 (16.79) | 94 (15.82) | 112 (17.69) |  |
 Civil servants, teachers and other intellectuals | 264 (21.52) | 110 (18.52) | 154 (24.33) |  |
 Businessmen | 172 (14.02) | 82 (13.80) | 90 (14.22) |  |
 Others | 199 (16.22) | 82 (13.80) | 107 (16.90) |  |
Job of father | Â | Â | Â | 0.411 |
 Workers | 534 (43.52) | 275 (46.30) | 259 (40.92) |  |
 Farmers | 131 (10.68) | 64 (10.77) | 67 (10.58) |  |
 Civil servants, teachers and other intellectuals | 237 (19.32) | 108 (18.18) | 129 (20.38) |  |
 Businessmen | 197 (16.06) | 94 (15.82) | 103 (16.27) |  |
 Others | 128 (10.43) | 53 (8.92) | 75 (11.85) |  |
Job of mother | Â | Â | Â | 0.008 |
 Workers | 431 (35.13) | 239 (40.24) | 192 (30.33) |  |
 Farmers | 243 (19.80) | 112 (18.86) | 131 (20.70) |  |
 Civil servants, teachers and other intellectuals | 185 (15.08) | 86 (14.48) | 99 (15.64) |  |
 Businessmen | 154 (12.55) | 72 (12.12) | 82 (12.95) |  |
 Others | 214 (17.44) | 85 (14.31) | 129 (20.38) |  |
PSQI (Mean ± SD) | 5.87 ± 2.94 | 5.75 ± 3.04 | 5.97 ± 2.86 | 0.010 |
STAI (Mean ± SD) | 84.10 ± 17.28 | 84.23 ± 17.76 | 83.98 ± 16.82 | 0.278 |
SDS (Mean ± SD) | 49.04 ± 10.85 | 48.87 ± 11.09 | 49.19 ± 10.62 | 0.228 |