Table 2.

Intercorrelations and Descriptive Statistics of Study Variables

Variable	1	2	3	4	5	6	7	8	9	10	11	12	13	14
1. Sex	--	−.14	−.05	−.40***	.14	.05	−.26*	.17	.07	−.24*	−.29**	−.14	−.02	−.08
2. Age		--	.16	.50***	−.29**	−.20	−.07	−.14	−.11	−.03	.02	−.02	.002	−.11
3. ADHD medication use			--	.09	−.18	−.21	−.01	.11	.12	−.07	−.21	−.17	.14	.02
4. Pubertal development				--	−.26*	−.20	.12	−.14	−.11	.11	.02	.22*	−.03	.10
5. ADHD symptoms					--	.56***	.04	.19	−.10	−.10	−.02	.20	.10	.22*
6. ODD symptoms						--	−.14	.07	−.07	−.10	.001	.20	.06	.16
7. Internalizing symptoms							--	−.17	−.08	.29**	.28*	.24*	.17	.31**
8. Circadian preference								--	.23*	−.51***	−.47***	−.32**	−.37**	−.36**
9. Weekday sleep duration									--	−.34**	−.23*	−.42***	−.28*	−.39***
10. SHS sleep/wake problems										--	.61***	.21	.34**	.35**
11. SHS sleepiness											--	.11	.31**	.21
12. SDSC DIMS												--	.29**	.72***
13. SDSC sleepiness													--	.74***
14. SDSC total														--
Mean	--	15.01	--	3.01	2.48	2.05	0.58	26.35	7.39	18.26	12.00	15.71	9.30	41.65
Standard Deviation	--	1.09	--	0.62	0.54	0.67	0.33	4.75	1.02	6.12	3.32	4.02	3.47	7.09
Minimum	0	13	0	1	1.22	1.00	0.00	16.00	4.50	10.00	9.00	9.00	5.00	28.00
Maximum	1	17	1	4	3.56	4.00	1.44	37.00	9.50	37.00	23.00	26.00	24.00	61.00

Note. For sex, 0 = female, 1 = male. For ADHD medication use, 0 = not prescribed stimulant medication, 1 = prescribed stimulant medication. For circadian preference, higher scores indicate greater morningness preference. For pubertal development, higher scores indicate more advanced pubertal development. ADHD = attention-deficit/hyperactivity disorder. DIMS = Difficulties Initiating and Maintaining Sleep. ODD = oppositional defiant disorder. SDSC = Sleep Disturbance Scale for Children. SHS = Sleep Habits Survey.

^*p < .05.

^**p < .01.

^***p < .001.