Table 1. Characteristics of the Participants by Sleep Duration Trajectory Group.
| Characteristics | Sleep duration trajectorya | |||
|---|---|---|---|---|
| Normal | Low | |||
| Stable | Decreasing | Increasing | Stable | |
| All participants | 40 262 (76.5) | 8047 (15.3) | 3384 (6.5) | 879 (1.7) |
| Age, mean (SD), y | 52.0 (11.9) | 53.5 (11.3) | 55.8 (11.6) | 57.1 (11.9) |
| Age ≥65 y | 5595 (13.9) | 1273 (15.8) | 734 (21.7) | 231 (26.3) |
| Female | 9872 (24.5) | 1740 (21.6) | 665 (19.7) | 235 (26.7) |
| Unmarried | 220 (0.5) | 33 (0.4) | 13 (0.4) | 3 (0.3) |
| Mean income ≥3000 RMB/mob | 4514 (11.7) | 901 (11.3) | 297 (8.9) | 63 (7.2) |
| Blue collar workerb | 32 837 (84.7) | 6518 (83.4) | 2880 (88.5) | 720 (84.2) |
| Educational attainment college or university | 4921 (12.2) | 957 (11.9) | 259 (7.7) | 72 (8.2) |
| Current smoker | 12 927 (32.1) | 3452 (42.9) | 1254 (37.1) | 344 (39.1) |
| Current alcohol user | 13 275 (33.0) | 3646 (45.3) | 1374 (40.6) | 398 (45.3) |
| Salt intake ≥10 g/d | 3705 (9.2) | 1196 (14.9) | 359 (10.6) | 147 (16.7) |
| Physical activity ≥3 times/wk | 5205 (12.9) | 1492 (18.5) | 587 (17.3) | 191 (21.7) |
| Hypertension | 5175 (12.9) | 1684 (20.9) | 684 (20.2) | 247 (28.1) |
| Diabetes | 1505 (3.7) | 484 (6.0) | 194 (5.7) | 73 (8.3) |
| Hyperlipidemia | 1880 (4.7) | 672 (8.4) | 215 (6.4) | 95 (10.8) |
| Frequent snoring | 4772 (11.9) | 1734 (21.5) | 574 (17.0) | 188 (21.4) |
| Medication usea | ||||
| Antihypertensive | 3674 (9.2) | 1194 (14.9) | 499 (14.9) | 189 (21.7) |
| Hypoglycemic | 1089 (2.7) | 358 (4.5) | 145 (4.3) | 55 (6.3) |
| Agents to lower lipid levels | 306 (0.8) | 107 (1.3) | 29 (0.9) | 12 (1.4) |
| Family history | ||||
| Stroke | 882 (2.2) | 331 (4.1) | 77 (2.3) | 47 (5.3) |
| MI | 421 (1.0) | 163 (2.0) | 45 (1.3) | 19 (2.2) |
| BMI, mean (SD)c | 24.9 (3.2) | 25.0 (3.1) | 25.1 (3.2) | 25.0 (3.3) |
| hs-CRP level, mg/dLc,d | 1.6 | 1.6 | 1.7 | 1.5 |
| Blood pressure, mm Hg, mean (SD)c | ||||
| SBP | 129.0 (16.9) | 129.0 (16.3) | 131.9 (17.2) | 131.4 (17.1) |
| DBP | 83.5 (9.3) | 83.4 (8.9) | 84.3 (9.1) | 83.8 (9.2) |
| FBG level, mean (SD), mg/dLc | 99.1 (25.2) | 99.1 (23.4) | 100.9 (27.0) | 99.1 (25.2) |
| eGFR, mean (SD), mL/min/1.73 m2 | 87.6 (18.5) | 91.7 (16.6) | 88.9 (17.7) | 90.3 (16.6) |
| Sleep duration, mean (SD), h | ||||
| Year 2006 | 7.5 (0.8) | 6.9 (0.9) | 4.9 (0.9) | 4.9 (1.3) |
| Year 2008 | 7.5 (0.9) | 6.0 (1.0) | 6.0 (1.2) | 4.2 (1.5) |
| Year 2010 | 7.4 (0.8) | 5.5 (0.8) | 6.9 (0.9) | 4.2 (1.4) |
Abbreviations: BMI, body mass index (calculated as weight in kilograms divided by height in square meters); DBP, diastolic blood pressure; eGFR, estimated glomerular filtration rate; FBG, fasting blood glucose; hs-CRP, high-sensitivity C-reactive protein; MI, myocardial infarction; RMB, renminbi; SBP, systolic blood pressure.
SI conversion factors: To convert CRP to mg/L, multiply by 10; glucose to mmol/L, multiply by 0.0555.
Unless otherwise indicated, data are expressed as number (percentage) of patients. The normal-stable sleep duration pattern ranged from 7.4 to 7.5 hours per night; low-increasing pattern, mean increase from 4.9 to 6.9 hours per night; normal-decreasing pattern, mean decrease from 7.0 to 5.5 hours per night; and low-stable pattern, range of 4.9 to 4.2 hours per night.
Variable had missing value. Data were missing for income for 947 participants (1.8%), occupation for 1894 (3.6%), use of antihypertensives for 421 (0.8%), and use of hypoglycemics for 210 (0.4%).
Mean data based on measures in 2006, 2008, and 2010.
Indicates geometric mean.