Table 3.

F-Statistics and p-values for key predictors in linear mixed models for weekday and weekend sleep duration

	F*	P		F †	P
Later elementary school (Grades 3–5)
Weekday sleep duration			Weekday sleep duration
Year	55.55	<0.0001	Year	43.76	<0.0001
Race	28.31	<0.0001	FRL	32.28	<0.0001
Race × year	2.41	0.0155	FRL × year	1.50	0.2304
Weekend sleep duration			Weekend sleep duration
Year	0.32	0.7265	Year	0.01	0.9922
Race	2.00	0.0967	FRL	1.39	0.2457
Race × year	2.18	0.0290	FRL × year	1.73	0.1835
Middle school (Grades 6–8)
Weekday sleep duration			Weekday sleep duration‡
Year	121.55	<0.0001	Year	325.02	<0.0001
Race	6.12	0.0006	FRL	0.00	0.9812
Race × year	1.29	0.2607	FRL × year	2.72	0.0657
Weekend sleep duration			Weekend sleep duration
Year	0.45	0.6468	Year	0.97	0.3969
Race	1.21	0.3201	FRL	3.36	0.0968
Race × year	2.09	0.0475	FRL × year	0.57	0.5756
High school (Grades 9–12)
Weekday sleep duration			Weekday sleep duration
Year	252.36	<0.0001	Year	202.31	<0.0001
Race	18.82	<0.0001	FRL	7.39	0.0418
Race × year	1.31	0.2656	FRL × year	1.15	0.3546
Weekend sleep duration			Weekend sleep duration
Year	3.07	0.0911	Year	11.89	0.0023
Race	1.28	0.3124	FRL	4.94	0.0768
Race × year	3.22	0.0064	FRL × year	4.35	0.0436

Results for models with race are shown on left, those with FRL status on right. The ecological modeling approach was used to obtain results, unless otherwise noted.

*Numerator DF were as follows: Year = 2, Race = 4, Year × Race = 8; denominator DF ranged from 80 to 314.

^†Numerator DF were as follows: Year = 2, FRL = 1, Year x FRL = 1; denominator DF ranged from 41 to 80.

^‡Standard models did not converge, so for these conditions, so the unit modeling approach described in the methods section is reported.