Table 1. Participants characteristic according to the categories of social jetlag

	Social jetlag
Participants characteristics	<1 h	1 to <2 h	≥2 h	P-value* for trend
Number of subjects	892	399	113
Age (mean ± SD, y)	46.2 ± 9.4	42.9 ± 9.6	39.7 ± 10.8	<0.001
Sex (women, %)	13.3	17.8	20.4	0.009
Work (survey in April 2015, %)	52.9	54.1	54.9	0.61
Flexible time work (yes, %)	18.2	22.6	19.5	0.20
Marital status (married, %)	75.0	60.9	39.8	<0.001
Employment type (regular, %)	91.1	94.0	90.3	0.47
Blue-collar workers (%)	29.2	35.9	40.7	<0.001
Job grade (low, %)	83.6	88.5	92.9	<0.001
Overtime (≥30 h/mo, %)	22.3	22.1	19.5	0.58
Current smoker (%)	23.5	29.3	34.5	0.002
Current alcohol drinker (≥1 d/wk, %)	56.3	44.6	48.7	<0.001
Work-related physical activity (≥20 METs-h/d, %)	14.2	21.1	20.3	0.003
Leisure-time physical activity (≥10 METs-h/wk, %)	29.4	24.1	18.6	0.004
BMI (kg/m2)	23.5 ± 3.4	23.4 ± 3.7	23.9 ± 4.0	0.66
Dietary intake (per d)
Total energy (mean ± SD, kcal)	1819 ± 508	1768 ± 545	1770 ± 613	0.11
Magnesium (mg/1,000 kcal)	128 ± 25	124 ± 26	122 ± 27	0.002
Calcium (mg/1,000 kcal)	248 ± 91	230 ± 85	228 ± 103	<0.001
Iron (mg/1,000 kcal)	3.9 ± 1.0	3.8 ± 1.0	3.7 ± 1.0	0.02
Zinc (mg/1,000 kcal)	4.2 ± 0.6	4.2 ± 0.67	4.2 ± 0.7	0.09
Folate (µg/1,000 kcal)	163 ± 57	157 ± 56	151 ± 50	0.008
Vitamin C (mg/1,000 kcal)	49 ± 23	48 ± 24	44 ± 22	0.04
Vitamin B6 (mg/1,000 kcal)	0.63 ± 0.19	0.62 ± 0.22	0.60 ± 0.23	0.21
Vitamin B12 (µg/1,000 kcal)	4.7 ± 2.3	4.5 ± 2.3	4.5 ± 2.6	0.25
ω-3 PUFA (% energy)	1.2 ± 0.4	1.2 ± 0.4	1.2 ± 0.4	0.07
Sleep duration (mean ± SD, h/d)	6.5 ± 0.9	6.5 ± 0.8	6.7 ± 1.1	0.22
Average sleep quality (bad, %)	32.3	39.1	43.4	0.002
Chronotype (mean ± SD, h:min)	2:56 ± 0.58	3:52 ± 0.57	4:54 ± 0.95	<0.001
CES-D score [median (IQR)]	11 (7–16)	12 (8–17)	14 (10–20)	<0.001

IQR, Interquartile range; PUFA, polyunsaturated fatty acids.

*Based on Mantel–Haenszel chi-square test for categorical variables and linear regression analysis for continuous variables.