BMC Public Health 2009, 9:130 http://www.biomedcentral.com/1471-2458/9/130 Table 2: Characteristics of the study participants by quality of sleep Variable, N (%) Female gender Beijing region Rural residence Age, mean(std) Age category, years 50≤ age <60 60≤ age ≤70 BMI, mean(std) BMI category Under weight Normal Over weight/Obese Currently married (YES, %) Living alone (YES, %) Smoking Current Former Never Current alcohol drinker Physical activity, level Low Moderate High Educational level, years in school 0–6 7–9 ≥10 Medical insurance (YES, %) Annual income, Yuan <10000 10000–29999 ≥30000 Employment Employed Retired Unemployed/on welfare Social activities (YES, %) Self-rated health status (good, %) Diabetes (YES, %) Metabolic syndrome (YES, %) Hyperlipidemia (YES, %) Cardiovascular disease (YES, %) Pulmonary disease (YES, %) Arthritis (YES, %) Prostatism (YES, %) Depressive symptoms (YES, %) Sleeping pills intake (YES, %) Having nap (YES, %) Sleep quantity, total hours of sleep/day <7 7–9 >9 Total 1819(55.71) 1628(49.86) 1638(50.17) 58.59 (6.01) 1845(56.51) 1420(43.49) 24.46 (3.59) 111 (3.40) 1411(43.22) 1743(53.38) 2862(87.66) 185(5.67) 910(27.87) 326(9.98) 2029(62.14) 930(28.48) 242(7.41) 1368(41.90) 1655(50.69) 1348(41.29) 1163(35.62) 754(23.09) 2280(70.05) 903(29.07) 1409(45.36) 794(25.56) 778(23.83) 1803(55.22) 684(20.95) 1661(50.87) 1041(31.90) 446(14.04) 1392(42.63) 430(13.78) 327(10.24) 238(7.33) 431(13.41) 150(10.81) 307(9.40) 97(2.97) 1382(42.33) 799(24.47) 2208(67.63) 258(7.90) Well 849(48.91) 757(43.61) 956(55.07) 58.61 (6.05) 975(56.16) 761(43.84) 24.33 (3.50) 61 (3.51) 776 (44.70) 889 (51.79) 1547(89.11) 89(5.13) 550(31.68) 184(10.60) 1002(57.72) 524(30.18) 120(6.91) 681(39.23) 935(53.86) 762(43.89) 599(34.50) 375(21.60) 1236(71.40) 512(31.05) 718(43.54) 419(25.41) 473(27.25) 905(52.13) 358(20.62) 910(52.42) 754(43.46) 211(12.48) 694(39.98) 175(10.45) 122(7.17) 111(6.43) 175(10.21) 66(7.78) 49(2.82) 12(0.69) 739(42.57) 209(12.04) 1348(77.65) 179(10.31) Abbreviations: SD, standard deviation; BMI, Body Mass Index; CI, Confidence interval. *Data are given as frequency (percentage) unless otherwise indicated. Common 603(60.24) 558(55.74) 420(41.96) 58.69(6.00) 554(55.34) 447(44.66) 24.66(3.68) 27 (2.70) 423 (42.26) 551 (55.04) 858(85.71) 63(6.29) 241(24.08) 98(9.79) 662(66.13) 293(29.27) 74(7.39) 455(45.45) 472(47.15) 366(36.56) 371(37.06) 264(26.37) 711(71.24) 239(24.82) 469(48.70) 255(26.48) 207(20.68) 598(59.74) 196(19.58) 508(50.75) 203(20.30) 154(15.81) 451(45.05) 169(17.81) 103(10.59) 77(7.73) 144(14.69) 55(14.36) 116(11.59) 21(2.10) 428(42.76) 273(27.27) 668(66.73) 60(5.99) Poor 367(69.51) 313(59.28) 262(49.62) 58.34(5.90) 316(59.85) 212(40.15) 24.53(3.66) 23 (4.36) 212 (40.15) 293 (55.49) 457(86.55) 33(6.25) 119(22.54) 44(8.33) 365(69.13) 113(21.40) 48(9.09) 232(43.94) 248(46.97) 220(41.67) 193(36.55) 115(21.78) 333(63.31) 152(30.77) 222(44.94) 120(24.29) 98(18.56) 300(56.82) 130(24.62) 243(46.02) 84(15.91) 81(15.85) 247(46.78) 86(17.30) 102(19.69) 50(9.52) 112(21.54) 29(18.59) 142(26.89) 64(12.12) 215(40.72) 317(60.04) 192(36.36) 19(3.60) P-value <.0001 <.0001 <.0001 0.5617 0.2195 0.056 0.1373 0.0237 0.3664 <.0001 0.0004 0.0025 0.0026 0.0011 0.0116 <.0001 0.0362 <.0001 0.0255 0.0038 <.0001 <.0001 0.0501 <.0001 <.0001 <.0001 <.0001 0.7131 <.0001 Page 5 of 11 (page number not for citation purposes)