Table 1. Demographics of final analytic sample (N=7,995).

Continuous variables are reported as mean ± standard deviation (min – max) or median ± IQR for variables with outliers or likely errors. All variables unless otherwise noted are from the baseline assessment.

Total N	7995
Sex (% Female)	49.52%
Age (in years)	9.49 ± 0.51 (8–11)
Race (% White)	76.36%
Puberty Development Score	6.74 ± 2.87 (1–20)
Body mass index	17.51 (15.89–20.34)
% with caffeine consumption in past 24 hours	17.44%
% with prescription medication use in past 24 hours	14.25%
% with over-the-counter medications use in past 24 hours	15.25%
Sleep duration (hours per night)	9–11 hours: 48.73% 8–9 hours: 37.19% 7–8 hours: 10.88% 5–7 hours: 2.96% <5 hours: 0.24%
Current grade	1st grade: 0.025% 2nd grade: 0.39% 3rd grade: 17.12% 4th grade: 44.61% 5th grade: 34.75% 6th grade: 3.08% 7th grade: 0.025%
Highest parental education	3rd grade: 0.038% 4th grade: 0.026% 5th grade: 0.026% 6th grade: 0.34% 7th grade: 0.12% 8th grade: 0.35% 9th grade: 0.70% 10th grade: 0.69% 11th grade: 0.84% 12th grade (no diploma): 1.27% High school graduate: 6.26% GED or equivalent: 2.36% Some College Degree: 12.29% Associate Degree (Occupational, Technical, or Vocational): 7.29% Associate Degree (Academic Program): 5.11% Bachelor’s Degree: 25.83% Master’ s Degree: 25.11% Professional School Degree: 5.34% Doctoral Degree: 6.01%
Weekend daily screen time (hours)	3.78 ± 2.58 (0–24)
Parental marital status	Married: 70.58% Never Married: 10.96% Divorced: 8.63% Living with Partner: 5.45% Separated: 3.61% Widowed: 0.77%
Combined family income, past year	<$5k: 2.82% $5k – $12k: 2.99% $12k – $16k: 2.31% $16k – $25k: 4.06% $25k – $35k: 5.50% $35k – $50k: 7.65% $50k – $75k: 12.68% $75k – $100k: 21.94% $100k – $200k: 28.86% >$200k: 11.19%
% parental history of depression	30.68%
Family Conflict Scores	2.50 ± 1.96 (0–9)
CBCL (Youth) Depression (t-score) Baseline Follow-up	53.54 ± 5.67 (50–89) 53.87 ± 6.02 (50–87)