Table 3.

Comparison of the neurocognitive function during the daytime work and after the night shift work of firefighters according to the Insomnia Severity Index (ISI) category.

Domain	ISI Category	N	Mean ± SD (n = 352)		p-Value
			During Daytime Work	Post Nighttime Work
Composite memory	Normal	186	90.2 ± 20.1	84.8 ± 19.5	<0.001
	Mild insomnia	134	90.6 ± 17.2	85.4 ± 19.4	0.002
	Insomnia	32	92.8 ± 21.6	81.5 ± 21.9	0.012
Verbal memory	Normal	186	87.7 ± 20.6	82.7 ± 22.5	<0.001
	Mild insomnia	134	87.4 ± 19.1	80.4 ± 20.3	<0.001
	Insomnia	32	89.7 ± 20.1	77.2 ± 24.6	0.001
Visual memory	Normal	186	96.6 ± 16.8	92.8 ± 15.8	0.006
	Mild insomnia	134	97.6 ± 14.9	95.8 ± 17.1	0.269
	Insomnia	32	98.3 ± 18.9	92.8 ± 18.6	0.110
Complex attention	Normal	186	96.1 ± 20.3	94.3 ± 23.7	0.260
	Mild insomnia	134	100.1 ± 15.0	92.2 ± 43.3	0.027
	Insomnia	32	98.2 ± 17.0	92.7 ± 22.4	0.227
Psychomotor speed	Normal	186	111.7 ± 16.5	110.2 ± 15.9	0.056
	Mild insomnia	134	114.1 ± 14.5	111.5 ± 14.5	0.008
	Insomnia	32	109.3 ± 11.3	104.3 ± 13.5	0.069
Motor speed	Normal	186	110.1 ± 15.8	108.6 ± 14.7	0.053
	Mild insomnia	134	112.2 ± 14.8	108.3 ± 13.5	0.001
	Insomnia	32	111.4 ± 12.1	104.8 ± 13.6	0.007
Processing speed	Normal	186	107.7 ± 15.9	106.5 ± 16.9	0.298
	Mild insomnia	134	109.1 ± 15.9	110.2 ± 17.4	0.341
	Insomnia	32	100.8 ± 11.3	101.4 ± 15.0	0.845
Reaction time	Normal	186	92.4 ± 15.2	92.3 ± 16.8	0.931
	Mild insomnia	134	93.5 ± 15.2	93.3 ± 17.3	0.872
	Insomnia	32	88.5 ± 12.3	93.0 ± 19.2	0.190
Cognitive flexibility	Normal	186	104.8 ± 18.8	105.1 ± 18.9	0.809
	Mild insomnia	134	108.4 ± 14.0	106.8 ± 20.1	0.306
	Insomnia	32	105.3 ± 15.4	106.0 ± 15.8	0.821
Executive functioning	Normal	186	105.6 ± 18.3	106.6 ± 18.3	0.426
	Mild insomnia	134	109.2 ± 13.8	108.0 ± 19.8	0.414
	Insomnia	32	105.8 ± 15.2	108.0 ± 14.7	0.397
Neurocognitive index	Normal	186	99.0 ± 13.0	97.3 ± 12.7	0.009
	Mild insomnia	134	101.4 ± 9.6	97.9 ± 14.9	0.001
	Insomnia	32	98.9 ± 10.9	95.4 ± 10.3	0.089

All subgroups were analyzed by paired t-test.