Table 3.

Longitudinal effects of work organization on insomnia.

Source	All participants			Insomnia occurrence			Insomnia resolution
	OR estimates	Confidence interval	p value	OR estimates	Confidence interval	p value	OR estimates	Confidence interval	p value
Shift work experience
Never	1	Reference	< 0.0001	1	Reference	0.0435	- *
< 5 years	3.51	(2.28–5.40)		1.71	(1.20–2.43)		1	Reference	0.0066
5–9 years	3.69	(2.34–5.84)		1.46	(0.86–2.49)		1.64	(1.16–2.32)
10–14 years	3.14	(1.90–5.18)		1.93	(0.96–3.89)		2.14	(1.25–3.68)
15–19 years	2.76	(1.53–4.97)		1.41	(0.62–3.19)		1.32	(0.59–2.98)
≥ 20 years	2.59	(1.32–5.06)		1.05	(0.34–3.20)		0.72	(0.22–2.36)
Quick return
No	1	Reference	0.039	1	Reference	0.7678	1.07	(0.84–1.36)	0.5784
Yes	1.13	(1.01–1.28)		1.03	(0.84–1.26)		1	Reference
Consecutive night shift
1 day	1	Reference	< 0.0001	1	Reference	0.05	0.64	(0.39–1.05)	0.3563
2 days	1.8	(1.45–2.24)		1.12	(0.81–1.55)		0.84	(0.53–1.34)
3 days	2.11	(1.74–2.55)		1.46	(1.11–1.91)		0.91	(0.63–1.31)
4 days	1.88	(1.32–2.67)		1.36	(0.80–2.32)		1.32	(0.62–2.77)
≥ 5 days	2.08	(1.68–2.59)		1.43	(1.01–2.03)		1	Reference
Nap opportunity
Yes	1	Reference	0.0362	1	Reference	0.0021	1.08	(0.68–1.74)	0.7372
No	1.24	(1.01–1.52)		1.65	(1.20–2.28)		1	Reference
Work-time control
Yes	1	Reference	< 0.0001	1	Reference	< .0001	1.14	(0.85–1.52)	0.3949
No	1.7	(1.49–1.94)		1.56	(1.27–1.91)		1	Reference
Weekly working hour
< 40 h	1	Reference	< 0.0001	1	Reference	0.9426	1.05	(0.46–2.39)	0.0166
40 h	1.17	(0.90–1.52)		0.98	(0.69–1.40)		0.7	(0.43–1.14)
41–51 h	1.88	(1.45–2.43)		0.98	(0.68–1.40)		0.53	(0.34–0.81)
52–59 h	1.96	(1.48–2.61)		1.1	(0.73–1.65)		0.64	(0.41–1.02)
≥ 60 h	1.89	(1.42–2.54)		0.98	(0.63–1.51)		1	Reference

The generalized estimating equation model includes age, sex, body mass index, smoking status, and drinking status as covariates.

*Due to lack of power, 25 records reporting no shift work experience were not included in this analysis.