Table 6.

Multilevel modeling results testing intervention effect on sleep problems

	Model 4A					Model 4B
	Coefficient γ	SE	t value	95% LL	95% UL	Coefficient γ	SE	t value	95% LL	95% UL
Intercept	34.35	4.17	8.23**	26.00	42.70	32.92	4.23	7.77**	24.45	41.39
Sophomorea	− 0.05	5.08	− 0.01	− 10.23	10.13	− 0.04	5.08	− 0.01	− 10.23	10.15
Juniora	− 3.99	3.82	− 1.04	− 11.64	3.66	− 3.99	3.82	− 1.04	− 11.64	3.67
Sex (male)	4.72	3.86	1.22	− 3.02	12.46	4.72	3.87	1.22	− 3.03	12.46
Neuroticism	6.92	2.17	3.19**	2.58	11.27	6.92	2.17	3.19**	2.58	11.27
Extraversion	1.93	1.79	1.08	− 1.66	5.53	1.94	1.79	1.08	− 1.66	5.53
Trait mindfulness	− 0.16	2.42	− 0.06	− 5.00	4.68	− 0.17	2.42	− 0.07	− 5.01	4.68
Coronavirus worry	3.57	1.60	2.22*	0.35	6.78	3.57	1.61	2.22*	0.35	6.79
Time	− 0.77	0.44	− 1.76ϯ	− 1.64	0.10	0.09	0.61	0.14	− 1.14	1.31
Intervention	1.30	3.50	0.37	− 5.70	8.31	4.09	3.78	1.08	− 3.48	11.66
Intervention × time						− 1.65	0.85	− 1.94ϯ	− 3.35	0.05
− 2LL deviance	2607.2					2602.0
Residual	77.42	7.53	10.28**	63.98	93.68	77.54	7.55	10.27**	64.06	93.84
Intercept variance	152.01	38.30	3.97**	92.77	249.07	150.40	37.73	3.99**	91.98	245.92
Slope variance	7.47	2.21	3.38**	4.18	13.35	6.89	2.14	3.22**	3.75	12.66
Intercept-slope covariance	− 9.25	7.60	− 1.22	− 24.14	5.63	− 8.25	7.29	− 1.13	− 22.55	6.04

N = 69 (between subjects) and N = 355 (within subjects). LL/UL, lower/upper confidence interval limit

γ, multilevel regression coefficient, SE, standard error

Model 4A does not include the time × intervention coefficient, whereas Model 4B does

^aReference group = senior

^*p < .05; **p < .01; ϯp < .10