Table 2. Comparisons of participants’ clinical characteristics based on sleep duration.

Variables	Sleep duration < 7 h/day (n = 2486)	Sleep duration 7–9 h/day (n = 2087)	Sleep duration ≥ 9 h/day (n = 19)	P value
Age, years	45.0 ± 11.6	43.0 ± 11.2	38.1 ± 13.9	<0.001
Male	1490 (59.9)	1249 (61.4)	36 (49.3)	0.087
BMI, kg/m2	24.1 ± 3.5	23.8 ± 3.4	23.1 ± 3.9	0.003
BMI ≥ 27	449 (18.1)	405 (15.0)	10 (13.7)	0.018
SBP, mmHg	114.4 ± 15.3	114.0 ± 14.9	111.5 ± 15.3	0.225
DBP, mmHg	67.9 ± 10.5	67.5 ± 10.0	64.1 ± 10.5	0.003
FPG, mg/dL	90.0 ± 20.0	90.0 ± 18.0	92.6 ± 30.5	0.527
ALT, U/L	32.0 ± 31.5	31.8 ± 35.0	28.6 ± 23.3	0.691
Cholesterol, mg/dL	194.9 ± 37.2	192.5 ± 34.8	193.4 ± 34.1	0.078
Triglyceride, mg/dL	124.8 ± 84.4	121.3 ± 83.9	129.3 ± 106.6	0.322
HDL-C, mg/dL	49.6 ± 13.5	49.4 ± 13.1	51.6 ± 14.4	0.370
Cholesterol/HDL-C	4.2 ± 1.3	4.2 ± 1.3	4.1 ± 1.4	0.421
Creatinine, mg/dL	0.87 ± 0.18	0.87 ± 0.18	0.86 ± 0.18	0.760
eGFR <60	205 (8.2)	165 (8.1)	3 (4.1)	0.443
WBC count, 10^3/μL	6.1 ± 1.6	6.2 ± 3.4	6.4 ± 1.8	0.301
Uric acid, mg/dL	6.1 ± 1.5	6.0 ± 1.5	6.0 ± 1.6	0.462
Hypertension	231 (9.3)	160 (7.9)	6 (8.2)	0.237
Diabetes mellitus	163 (6.6)	112 (5.5)	6 (8.2)	0.258
Total PSQI	8.1 ± 3.2	5.1 ± 2.3	4.9 ± 2.6	<0.001
PSQI >5	1959 (78.8)	767 (37.7)	24 (32.9)	<0.001
Sleep duration, h/day	5.7 ± 0.8	7.4 ± 0.5	9.3 ± 0.6	<0.001
Current alcohol use	405 (16.3)	344 (16.9)	12 (16.4)	0.851
Current smoking	409 (16.5)	338 (16.6)	14 (19.2)	0.823
Exercise ≥ 3/wk	310 (12.5)	243 (12.0)	7 (9.6)	0.687

Data expressed as mean ± standard deviation or number (percent).

BMI: body mass index, SBP: systolic blood pressure, DBP: diastolic blood pressure, FPG: fasting plasma glucose, ALT: Alanine Aminotransferase, TC: total cholesterol, HDL-C, high-density lipoprotein-cholesterol, eGFR: estimated glomerular filtration rate, PSQI: Pittsburgh Sleep Quality Index