Table 1.

General characteristics of the study participants at baseline.

	Male (n = 606)		Female (n = 2009)		Total (n = 2615)
	N	(%)	N	(%)	N	(%)
Age, mean (range)	30.6	(23.0, 59.0)	27.1	(21.0, 59.0)	27.9	(21.0, 59.0)
BMI, mean (range)	24.4	(16.5, 37.4)	21.4	(14.2, 37.4)	22.1	(14.2, 37.4)
Smoke
Yes	136	(22.4)	2	(0.10)	138	(5.28)
No	470	(77.6)	2007	(99.9)	2477	(94.7)
Drink
< 1/week	180	(29.7)	1008	(50.2)	1188	(45.4)
1–2/week	374	(61.7)	911	(45.4)	1285	(49.1)
3–7/week	52	(8.58)	90	(4.48)	142	(5.43)
ISI score
0–7	461	(76.1)	1292	(64.3)	1753	(67.0)
8–14	124	(20.5)	563	(28.0)	687	(26.3)
15–21	18	(2.97)	135	(6.72)	153	(5.85)
22–28	3	(0.50)	19	(0.95)	22	(0.84)
Shift work experience
Never	45	(7.43)	230	(11.5)	275	(10.5)
< 5 years	474	(78.2)	1261	(62.8)	1735	(66.4)
5–9 years	33	(5.45)	289	(14.4)	322	(12.3)
10–14 years	12	(1.98)	136	(6.77)	148	(5.66)
15–19 years	16	(2.64)	82	(4.08)	98	(3.75)
≥ 20 years	26	(4.29)	11	(0.55)	37	(1.41)
Quick return
Yes	240	(39.6)	572	(28.5)	812	(31.1)
No	366	(60.4)	1437	(71.5)	1803	(69.0)
Consecutive night shift
1 day	275	(45.4)	443	(22.1)	718	(27.5)
2 days	99	(16.3)	226	(11.3)	325	(12.4)
3 days	136	(22.4)	1079	(53.7)	1215	(46.5)
4 days	16	(2.64)	44	(2.19)	60	(2.29)
≥ 5 days	80	(13.2)	217	(10.8)	297	(11.4)
Nap opportunity
Yes	286	(47.2)	249	(12.4)	535	(20.5)
No	320	(52.8)	1760	(87.6)	2080	(79.5)
Work-time control
Yes	389	(64.2)	794	(39.5)	1183	(45.2)
No	217	(35.8)	1215	(60.5)	1432	(54.8)
Weekly working hours
< 40 h	45	(7.43)	160	(7.96)	205	(7.84)
40 h	122	(20.1)	630	(31.4)	752	(28.8)
41–51 h	144	(23.8)	803	(40.0)	947	(36.2)
52–59 h	61	(10.1)	224	(11.2)	285	(10.9)
≥ 60 h	234	(38.6)	192	(9.56)	426	(16.3)