Table 3. Results of the Linear Mixed Effect Model for Questionnaires.

Questionnaire		Group effect		Time effect		Group×time
		β (95% CI)	p value	β (95% CI)	p value	β (95% CI)	p value
PSQI-K total score		−0.04 (−0.16, 0.08)	0.468	0.01 (−0.02, 0.04)	0.463	0.0007 (−0.05, 0.05)	0.983
	Sleep quality	−0.04 (−0.17, 0.09)	0.523	0.03 (−0.003, 0.07)	0.074	−0.08 (−0.15, −0.001)	0.032
	Sleep latency	−0.33 (−0.81, 0.16)	0.182	−0.04 (−0.17, 0.10)	0.577	−0.05 (−0.30, 0.20)	0.724
	Sleep duration	0.02 (−0.07, 0.10)	0.694	−0.01 (−0.04, 0.02)	0.641	0.02 (−0.03, 0.07)	0.513
	Sleep disturbance	−0.01 (−0.23, 0.21)	0.907	−0.06 (−0.14, 0.02)	0.168	0.04 (−0.11, 0.19)	0.654
K-GDS-30		−0.40 (−0.89, 0.08)	0.103	−0.10 (−0.22, 0.03)	0.121	−0.03 (−0.26, 0.20)	0.831
K-GAI		−0.32 (−0.72, 0.07)	0.107	−0.19 (−0.30, −0.07)	0.002	−0.06 (−0.29, 0.17)	0.615
Stress inventory		−0.03 (−0.08, 0.03)	0.305	−0.02 (−0.03, −0.001)	0.038	−0.01 (−0.04, 0.02)	0.388

β, beta coefficient; CI, confidence interval; K-GAI, Korean version of the Geriatric Anxiety Inventory; K-GDS, Korean version of the Geriatric Depression Scale; PSQI-K, Korean version of the Pittsburgh Sleep Quality Index.

The terms for time were defined as 0 for baseline, 1 for 6-month, and 2 for 12-month follow-up.