Table 1. Descriptive Statistics for Outcome, Predictor, and Control Variables by Assessment (n = 250).

Variable	Time 1 mean (SD) or %	Time 2 mean (SD) or %	Time 3 mean (SD) or %
Outcome variables
Verbal Comprehension	486.26 (12.59)	494.78 (11.88)	499.62(11.42)
Decision Speed	488.01 (15.87)	502.08 (16.41)	510.55 (16.86)
Predictor variables
Sleepiness	15.67 (5.00)	14.21 (4.73)	13.66 (4.20)
Sleep/Wake Problems	18.78 (6.02)	19.79 (7.58)	17.87 (6.01)
Moderators
Gender (boys)	49.00%	48.85%	48.85%
Ethnicity (African American)	35.46%	35.94%	35.94%
Total family income	3.87 (1.46)	3.89 (1.50)	4.10(1.46)
Mother's education	4.80 (0.94)	4.83 (0.97)	4.79 (1.06)
Father's education	4.66(1.01)	4.67 (1.04)	4.64(1.00)
Socioeconomic status composite	-0.002 (2.45)	0.012 (2.45)	0.105 (2.33)
Control variables
Child age (in months)	98.71 (8.64)	111.70(9.46)	123.30(11.99)
Puberty status	1.39 (0.33)	1.56(0.44)	1.72(0.56)