Characteristics of the study subjects by sleep duration groups
| Variable | <6 hours (n=100) | 6–7 hours (n=255) | >7 hours (n=45) | p Value |
| Sex (man) | 30 (30) | 88 (34.5) | 23 (51.1)*,** | 0.044 |
| Age (years) | 65.2±7.6 | 64.1±8.3 | 65.1±10.6 | 0.530 |
| LDL-C (mg/dL) | 115.8±30.4 | 119.2±31.3 | 119.6±40.0 | 0.643 |
| TC (mg/dL) | 197.2±34.9 | 197.0±34.2 | 198.0±45.4 | 0.984 |
| HDL-C (mg/dL) | 57.4±15.8 | 53.9±12.5 | 51.2±16.4 | 0.025 |
| TG (mg/dL) | 120.4±61.8 | 119.8±62.7 | 138.5±88.6 | 0.207 |
| High LDL-C | 33 (33) | 87 (34.1) | 15 (33.3) | 0.978 |
| High TC | 49 (49) | 125 (49.0) | 21 (47.7) | 0.941 |
| Low HDL-C | 13 (13) | 25 (9.8) | 14 (31.1)*,** | 0.001 |
| High TG | 22 (22) | 58 (22.7) | 14 (31.1) | 0.437 |
| Alcohol drinking | 15 (15) | 52 (20.4) | 11 (24.4) | 0.346 |
| Current Smoking | 10 (10) | 27 (10.6) | 6 (13.3) | 0.828 |
| Regular exercise | 80 (80) | 209 (81.9) | 39 (86.4) | 0.642 |
| Hypertension | 47 (47) | 125 (49.0) | 29 (64.4) | 0.122 |
| Diabetes | 25 (25) | 45 (17.6) | 9 (20.0) | 0.293 |
| Hyperlipidaemia | 69 (69) | 161 (63.1) | 30 (66.7) | 0.564 |
| SBP (mm Hg) | 129.9±16.5 | 128.6±16.7 | 133.3±25.2 | 0.216 |
| DBP (mm Hg) | 76.4±13.0 | 76.6±11.8 | 78.9±9.13 | 0.436 |
| BMI (kg/m2) | 24.3±3.9 | 24.6±3.4 | 25.1±3.6 | 0.394 |
| WC (cm) | 84.7±10.4 | 84.8±9.6 | 87.4±8.6 | 0.235 |
| WHtR | 0.5±0.1 | 0.6±0.1 | 0.6±0.1 | 0.417 |
| ALT (mg/dL) | 22.5±14.0 | 22.3±11.94 | 22.7±15.9 | 0.530 |
| Creatinine (mg/dL) | 0.8±0.3 | 0.8±0.3 | 1.0±0.9 | 0.920 |
| FPG (mg/dL) | 98.2±28.2 | 94.8±19.3 | 100.3±45.1 | 0.519 |
| Uric acid (mg/dL) | 5.6±1.3 | 5.8±1.4 | 6.1±1.4 | 0.101 |
Data expressed as mean±SD for continuous variables and n (%) for categorical variables.
*p Value<0.05 compared with <6 hours group, **p Value<0.05 compared with 6–7 hours group.
ALT, alanine transaminase; BMI, body mass index; DBP, diastolic blood pressure; FPG, fasting plasma glucose; high LDL-C, low-density lipoprotein ≥130 (mg/day); high TC, total cholesterol ≥200 (mg/day); high TG, triglyceride ≥150 (mg/day); low HDL-C, high-density lipoprotein ≤40 (mg/day); SBP, systolic blood pressure; WC, waist circumference; WHtR, waist-to-height ratio.