Table 1.

Basic characteristics of study participants

Basic characteristics	Men		Women
	N = 14945	%	N = 13859	%
Sleep problems
Yes	386	2.6	449	3.2
No	14593	97.4	13410	96.8
Commuting time
≤10	2124	14.2	1962	14.2
11–20	2987	19.9	3281	23.7
21-30	2974	19.9	2986	21.5
31-40	2490	16.6	2335	16.8
41-50	950	6.3	851	6.1
51-60	1601	10.7	1297	9.4
>60	1853	12.4	1147	8.3
Working hours (h)
≤40 hours	6104	40.8	6727	48.5
>40 hours	8875	59.2	7132	51.5
Period of employment
>1 year	4162	27.8	3568	25.7
1 month–1 year	1177	7.9	674	4.9
<1 month	9640	64.4	9617	69.4
Company size
<10 workers	8428	56.3	8824	63.7
11–50 workers	4347	29.0	4036	29.1
51–100 workers	1345	9.0	741	5.3
≥100 workers	859	5.7	258	1.9
Job satisfaction
Yes	11015	73.5	10438	75.3
No	3964	26.5	3421	24.7
Authority to working schedule
Possible	8659	57.8	7558	54.5
Impossible	6320	42.2	6301	45.5
Shift work
Yes	1315	8.8	801	5.8
No	13664	91.2	13058	94.2
Regularity of the commute
Yes	10902	72.8	10872	78.4
No	4077	27.2	2987	21.6
Income (million, KRW)
≤12	2499	16.7	4645	33.5
≤20 and > 12	3939	26.3	5652	40.8
≤30 and > 20	4733	31.6	2514	18.1
>30	3808	25.4	1048	7.6