Sleep disturbances and psychomotor retardation in the prediction of cognitive impairments in patients with major depressive disorder

Table 3 Simple mediation analysis for the relationship between sleep disturbances and processing speed

Mediating variable (M)	Independent variable (X)	Dependent variable (Y)	X→M	M→Y	Indirect effect1	Direct effect1
Retardation	Sleep disturbances	Processing speed	0.204a	-0.105b	-0.021 [-0.051, -0.002]1	-0.075 [-0.150, 0.0001]

^aP < 0.05.

^bP < 0.01.

¹Significant point estimates (P < 0.05) as determined by the exclusion of zero from the confidence interval.