Predictors of insomnia symptoms in police employees: a longitudinal investigation and comparison of personality and psychosocial work factors

Figures & data

Table 1. Descriptive statistics and internal consistency (N = 189–206)

Variable	α	Min	Max	M	SD
Job demands T1	.71	1.50	5.00	3.09	0.68
Control T1	.75	1.00	4.80	2.78	0.73
Social support T1	.82	1.20	5.00	3.95	0.73
Stress T1	.83	0.00	32.00	12.53	5.91
Overcommitment T1	.81	6.00	23.00	14.12	3.42
Neuroticism T1	.86	1.00	4.25	2.26	0.66
Extraversion T1	.81	1.83	4.83	3.64	0.54
Openness T1	.72	1.83	4.92	3.19	0.52
Agreeableness T1	.67	2.67	4.83	3.85	0.42
Conscientiousness T1	.79	2.58	4.92	3.86	0.43
Insomnia T1	.85	0.00	42.00	11.25	8.81
Insomnia T2	.84	0.00	38.00	10.63	8.51

T1 = baseline, T2 = 6-months follow-up.

Table 2. Correlations between all continuous variables (N = 189–206)

	1	2	3	4	5	6	7	8	9	10	11	12	13
1. Age	-
2. Job demands	−.09	-
3. Control	.17*	−.11	-
4. Support at work	−.14	−.10	.28**	-
5. Stress	−.19**	.29**	−.20**	−.26**	-
6. Overcommitment	.00	.53**	.03	−.16*	.51**
7. Neuroticism	−.04	.06	−.16*	−.28**	.66**	.37**	-
8. Extraversion	−.01	.04	.00	.15*	−.30**	−.05**	−.51**	-
9. Openness	.02	.03	.16*	.09	−.09	.51**	−.18*	.30**	-
10. Agreeableness	.09	−.02	−.03	.10	−.15*	−.03	−.25**	.26**	.21**	-
11. Conscientiousness	.02	.14	.10	.21**	−.33**	−.06	−.39**	.34**	.13	.21**	-
12. Insomnia T1	−.01	.20**	−.21**	−.25**	.46**	.43**	.48**	−.24**	.01	−.12	−.12	-
13. Insomnia T2	−.04	.17*	−.15*	−.22**	.40**	.39**	.47**	−.23**	−.02	.00	−.12	.73**	-

*p < .05 **p < .01 T1 = baseline, T2 = 6-months follow-up.

Table 3. Baseline variables associated with insomnia symptoms measured at six-month follow-up in police employees (N = 183–193)

Separate regression models		Insomnia T2
		Not adjusted for insomnia T1						Adjusted for insomnia T1
		β	SE B	p	95% CI B		R^2*	β	SE B	p	95% CI B		R^2*
					Lower	Upper					Lower	Upper
Job demands and resources							.07						.53
	Gender	.15	1.23	.041	0.11	4.97		.03	0.89	.540	−8.03	1.83
	Age	−.05	0.06	.519	−0.17	0.08		−.02	0.05	.755	−1.21	2.31
	Rotating shift	.01	1.45	.893	−2.66	3.05		.07	1.03	.247	−0.10	0.08
	Job demands	.13	0.90	.065	−0.11	3.45		.03	0.65	.511	−0.84	3.24
	Control	−.05	0.91	.522	−2.39	1.21		.06	0.66	.304	−0.85	1.71
	Support at work	−.19	0.87	.013	−3.87	−0.46		−.04	0.63	.414	−0.62	1.98
	Insomnia T1^a							.72	0.05	.000	−1.76	0.73
Stress and overcommitment							.21						.54
	Gender	.12	1.17	.076	−0.22	4.41		.02	0.91	.719	−1.47	2.13
	Age	.05	0.06	.535	−0.08	0.16		.01	0.05	.883	−0.08	0.10
	Rotating shift	.14	1.31	.067	−0.17	4.99		.09	1.01	.145	−0.51	3.46
	Stress	.27	0.12	.001	0.16	0.62		.06	0.09	.387	−0.10	0.26
	Overcommitment	.26	0.19	.001	0.27	1.03		.07	0.15	.248	−0.13	0.48
	Insomnia T1^a							.68	0.06	.000	0.54	0.77
Personality							.22						.55
	Gender	.06	1.27	.417	−1.48	3.55		−.01	0.97	.813	−2.14	1.68
	Age	−.04	0.06	.606	−0.15	0.09		−.02	0.04	.726	−0.10	0.07
	Rotating shift	.09	1.29	.232	−1.00	4.11		.08	0.98	.159	−0.55	3.31
	Neuroticism	.47	1.14	.000	4.04	8.53		.17	0.93	.016	0.43	4.09
	Extraversion	−.07	1.30	.365	−3.75	1.39		−.04	0.98	.520	−2.57	1.31
	Openness	.07	1.16	.340	−1.18	3.41		.00	0.88	.982	−1.76	1.72
	Agreeableness	.12	1.50	.103	−0.50	5.41		.13	1.13	.014	0.59	5.05
	Conscientiousness	.03	1.49	.673	−2.31	3.56		.00	1.12	.931	−2.31	2.12
	Insomnia T1^a							.66	0.06	.000	0.53	0.76

T1 = baseline, T2 = 6-months follow-up, R^2* = adjusted

Table 4. Integrated model for predictors of insomnia symptoms in police employees (N = 183)

		Insomnia T2
		Not adjusted for insomnia T1						Adjusted for insomnia T1
		β	SE B	p	95% CI B		R^2*	β	SE B	p	95% CI B		R^2*
					Lower	Upper					Lower	Upper
Integrated model							.26						.54
	Support at work	−.09	0.77	.199	−2.52	0.53		−.00	0.62	.950	−1.25	1.18
	Stress	.04	0.13	.706	−0.21	0.32		−.05	0.11	.489	−0.28	0.14
	Overcommitment	.24	0.19	.002	0.23	0.97		.07	0.15	.265	−0.13	0.47
	Neuroticism	.33	1.15	.000	2.12	6.65		.16	0.93	.023	0.30	3.96
	Insomnia T1^a							.65	0.06	.000	0.51	0.75

T1 = baseline, T2 = follow-up, R^2* = adjusted