Table 3.

Statistics of tests for the mediation of a mediating variable (grey matter volume) in the relationship between an independent variable (sleep disturbance) and a dependent variable (depressive symptom).

Brain region	Sobel test			Bootstrap approach
	Indirect effect			Total effect		Direct effect		Indirect effect
	Effect size	z value	p value	Effect size	p value	Effect size	p value	Effect size	p value
Left PostCG	0.6366	2.0268	0.0427*	1.6077	0.0012*	0.9711	0.0372*	0.6366	0.0148*
Left STG	0.8731	2.5191	0.0118*	1.6077	0.0020*	0.7347	0.1150	0.8731	0.0066*

PostCG, postcentral gyrus; STG, superior temporal gyrus; and *, statistical significance.