Distributions of sleep duration by categorical basic characteristics and descriptive statistics of continuous covariates in the sleep duration groups
| Variables | Sleep duration (hours) | Overall | χ2/F | P value | ||||
| <6 | 6 | 7 | 8 | ≥9 | ||||
| Subjects, n (%) | 9576 (17.20) | 8988 (16.14) | 11 159 (20.04) | 17 790 (31.95) | 8174 (14.67) | 55 687 (100) | – | |
| Gender, n (%) | ||||||||
| Female | 6271 (18.24) | 5273 (15.34) | 6594 (19.18) | 10 898 (31.71) | 5336 (15.53) | 34 372 (100) | 171.051 | <0.0001 |
| Male | 3305 (15.51) | 3715 (17.43) | 4565 (21.42) | 6892 (32.33) | 2838 (13.31) | 21 315 (100) | ||
| Age (years), n (%) | ||||||||
| 30–39 | 604 (6.21) | 998 (10.27) | 1802 (18.54) | 4142 (42.60) | 2176 (22.38) | 9722 (100) | 4406.276 | <0.0001 |
| 40–49 | 1651 (11.01) | 2087 (13.91) | 3170 (21.13) | 5523 (36.82) | 2571 (17.13) | 15 002 (100) | ||
| 50–59 | 3560 (19.69) | 3278 (18.13) | 3815 (21.11) | 5262 (29.11) | 2161 (11.96) | 18 076 (100) | ||
| 60–69 | 2775 (27.41) | 2050 (20.25) | 1962 (19.38) | 2340 (23.12) | 996 (9.84) | 10 123 (100) | ||
| 70–79 | 986 (35.67) | 575 (20.80) | 410 (14.83) | 523 (18.92) | 270 (9.78) | 2764 (100) | ||
| Education level, n (%) | ||||||||
| No formal school | 2610 (30.38) | 1555 (18.10) | 1452 (16.90) | 1942 (22.60) | 1033 (12.02) | 8592 (100) | 2440.546 | <0.0001 |
| Primary school | 5146 (18.53) | 4759 (17.14) | 5539 (19.95) | 8401 (30.26) | 3920 (14.12) | 27 765 (100) | ||
| Middle school | 1444 (9.70) | 2040 (13.70) | 3059 (20.55) | 5722 (38.44) | 2621 (17.61) | 14 886 (100) | ||
| High school and above | 376 (8.46) | 634 (14.27) | 1109 (24.95) | 1725 (38.82) | 600 (13.50) | 4444 (100) | ||
| Occupation, n (%) | ||||||||
| Farmer | 8674 (17.73) | 7862 (16.07) | 9629 (19.68) | 15 531 (31.74) | 7236 (14.78) | 48 932 (100) | 102.183 | <0.0001 |
| Others | 902 (13.35) | 1126 (16.67) | 1530 (22.65) | 2259 (33.44) | 938 (13.89) | 6755 (100) | ||
| Marital status, n (%) | ||||||||
| Married | 8040 (15.91) | 7990 (15.81) | 10 236 (20.26) | 16 610 (32.87) | 7650 (15.15) | 50 526 (100) | 797.729 | <0.0001 |
| Never married/widowed/separated/divorced | 1536 (29.76) | 998 (19.34) | 923 (17.88) | 1180 (22.86) | 524 (10.16) | 5161 (100) | ||
| Annual household income (¥), n (%) | ||||||||
| <5000 | 3730 (24.61) | 2454 (16.19) | 2761 (18.22) | 3996 (26.37) | 2215 (14.61) | 15 156 (100) | 991.831 | <0.0001 |
| 5000–9999 | 3145 (15.98) | 3168 (16.09) | 3867 (19.65) | 6532 (33.18) | 2972 (15.10) | 19 684 (100) | ||
| ≥10 000 | 2701 (12.96) | 3366 (16.15) | 4531 (21.73) | 7262 (34.83) | 2987 (14.33) | 20 847 (100) | ||
| Tea consumption, n (%) | ||||||||
| Never or almost never | 2311 (23.51) | 1534 (15.61) | 1768 (17.99) | 2692 (27.39) | 1525 (15.50) | 9830 (100) | 581.800 | <0.0001 |
| Only occasionally | 4822 (17.76) | 4488 (16.53) | 5385 (19.83) | 8695 (32.02) | 3764 (13.86) | 27 154 (100) | ||
| Usually at least once a week | 2443 (13.06) | 2966 (15.86) | 4006 (21.42) | 6403 (34.24) | 2885 (15.42) | 18 703 (100) | ||
| Smoking status, n (%) | ||||||||
| Never | 4896 (16.38) | 4418 (14.78) | 5771 (19.30) | 9998 (33.44) | 4814 (16.10) | 29 897 (100) | 350.690 | <0.0001 |
| Ex-regular smoker | 835 (22.14) | 675 (17.90) | 786 (20.84) | 996 (26.41) | 479 (12.71) | 3771 (100) | ||
| Occasional smoker | 892 (20.14) | 827 (18.67) | 892 (20.14) | 1272 (28.71) | 547 (12.34) | 4430 (100) | ||
| Daily or almost every day | 2953 (16.79) | 3068 (17.44) | 3710 (21.09) | 5524 (31.41) | 2334 (13.27) | 17 589 (100) | ||
| Alcohol intake, n (%) | ||||||||
| Never regular drinker | 3591 (18.80) | 2926 (15.32) | 3575 (18.72) | 6031 (31.56) | 2979 (15.60) | 19 102 (100) | 204.099 | <0.0001 |
| Ex-regular drinker | 463 (22.43) | 371 (17.97) | 439 (21.27) | 512 (24.81) | 279 (13.52) | 2064 (100) | ||
| Occasional or seasonal drinker | 3548 (16.40) | 3456 (15.97) | 4439 (20.51) | 7118 (32.89) | 3078 (14.23) | 21 639 (100) | ||
| Usually at least once a week | 1974 (15.32) | 2235 (17.35) | 2706 (21.01) | 4129 (32.05) | 1838 (14.27) | 12 882 (100) | ||
| Fresh fruit consumption, n (%) | ||||||||
| Daily | 736 (11.53) | 863 (13.52) | 1376 (21.56) | 2218 (34.76) | 1188 (18.63) | 6381 (100) | 1185.806 | <0.0001 |
| 4–6 days/week | 716 (12.75) | 814 (14.50) | 1134 (20.20) | 1931 (34.39) | 1020 (18.16) | 5615 (100) | ||
| 1–3 days/week | 3688 (15.35) | 3720 (15.49) | 4654 (19.38) | 8347 (34.75) | 3611 (15.03) | 24 020 (100) | ||
| Monthly | 3401 (21.93) | 2890 (18.63) | 3210 (20.69) | 4262 (27.48) | 1748 (11.27) | 15 511 (100) | ||
| Never/rarely | 1035 (24.88) | 701 (16.85) | 785 (18.87) | 1032 (24.81) | 607 (14.59) | 4160 (100) | ||
| BMI (kg/m2), n (%) | ||||||||
| <18.5 | 625 (25.31) | 436 (17.66) | 462 (18.71) | 642 (26.00) | 304 (12.32) | 2469 (100) | 161.222 | <0.0001 |
| 18.5–23.9 | 5523 (17.33) | 5094 (15.99) | 6399 (20.08) | 10 209 (32.04) | 4642 (14.56) | 31 867 (100) | ||
| 24–27.9 | 2700 (16.12) | 2718 (16.23) | 3393 (20.26) | 5416 (32.34) | 2519 (15.05) | 16 746 (100) | ||
| ≥28 | 728 (15.81) | 740 (16.07) | 905 (19.65) | 1523 (33.07) | 709 (15.40) | 4605 (100) | ||
| DM, n (%) | ||||||||
| No | 9050 (16.89) | 8606 (16.06) | 10 751 (20.07) | 17 257 (32.21) | 7908 (14.77) | 53 572 (100) | 118.858 | <0.0001 |
| Yes | 526 (24.87) | 382 (18.06) | 408 (19.29) | 533 (25.20) | 266 (12.58) | 2115 (100) | ||
| CHD, n (%) | ||||||||
| No | 9501 (17.15) | 8929 (16.11) | 11 101 (20.03) | 17 734 (32.00) | 8147 (14.71) | 55 412 (100) | 37.361 | <0.0001 |
| Yes | 75 (27.27) | 59 (21.45) | 58 (21.09) | 56 (20.36) | 27 (9.83) | 275 (100) | ||
| Stroke, n (%) | ||||||||
| No | 9509 (17.17) | 8941 (16.14) | 11 115 (20.06) | 17 719 (31.99) | 8112 (14.64) | 55 396 (100) | 23.279 | 0.0001 |
| Yes | 67 (23.02) | 47 (16.15) | 44 (15.12) | 71 (24.40) | 62 (21.31) | 291 (100) | ||
| Hypertension, n (%) | ||||||||
| No | 6530 (15.67) | 6527 (15.66) | 8473 (20.33) | 13 865 (33.27) | 6278 (15.07) | 41 673 (100) | 362.709 | <0.0001 |
| Yes | 3046 (21.74) | 2461 (17.56) | 2686 (19.17) | 3925 (28.01) | 1896 (13.52) | 14 014 (100) | ||
| Age (years), mean (SD) | 56.30±9.94 | 53.37±10.19 | 50.80±10.07 | 48.60±10.09 | 47.90±10.31 | 51.03±10.54 | 1224.030 | <0.0001 |
| MET (hours/day), mean (SD) | 21.08±11.47 | 21.98±11.89 | 22.67±12.03 | 22.72±11.65 | 21.12±11.70 | 22.07±11.76 | 51.170 | <0.0001 |
| WC (cm), mean (SD) | 77.45±9.27 | 78.27±9.11 | 78.16±8.98 | 78.07±8.96 | 77.99±9.05 | 78.00±9.06 | 11.800 | <0.0001 |
| BMI (kg/m2), mean (SD) | 23.00±3.29 | 23.29±3.21 | 23.32±3.18 | 23.38±3.15 | 23.39±3.19 | 23.29±3.20 | 25.120 | <0.0001 |
| Sedentary leisure time (hours/week), mean (SD) | 25.15±10.22 | 25.83±10.45 | 25.98±10.50 | 26.85±10.53 | 27.28±11.39 | 26.28±10.61 | 64.490 | <0.0001 |
| SBP (mm Hg), mean (SD) | 132.28±20.24 | 130.23±19.23 | 128.61±18.73 | 127.81±18.18 | 128.52±18.96 | 129.24±19.01 | 99.140 | <0.0001 |
| DBP (mm Hg), mean (SD) | 77.65±10.51 | 77.34±10.34 | 76.96±10.24 | 77.02±9.97 | 77.45±10.28 | 77.23±10.23 | 8.940 | <0.0001 |
The percentages in the table are row percent. χ2 tests were conducted to test for differences in percentage for categorical variables. One-way analysis of variance (ANOVA) tests were conducted to test for differences in means for categorical variables.
BMI, body mass index; CHD, coronary heart disease; DBP, diastolic blood pressure; DM, diabetes mellitus; MET, metabolic equivalent; SBP, systolic blood pressure; SD, standard deviation; WC, waist circumference.