TABLE 1.
Parent, Household, and Child Characteristics According to Actigraphy-Estimated Sleep Duration in Early Adolescence
| Characteristics | Overall, n = 829 | <480 min per d, n = 692 | ≥480 min per d, n = 137 |
|---|---|---|---|
| Mother and/or household characteristics, mean (SD) | |||
| Maternal age at enrollment, y | 32.3 (5.0) | 32.3 (5.1) | 32.6 (4.7) |
| Mother graduated college, n (%) | |||
| No | 228 (27.5) | 198 (28.7) | 30 (21.9) |
| Yes | 600 (72.5) | 493 (71.3) | 107 (78.1) |
| Household income >$70 000 per y at early teenager visit, n (%) | |||
| No | 177 (22.2) | 154 (23.1) | 23 (17.4) |
| Yes | 622 (77.8) | 513 (76.9) | 109 (82.6) |
| Adolescent’s characteristics | |||
| Girl, n (%) | |||
| No | 402 (48.5) | 357 (51.6) | 45 (32.8) |
| Yes | 427 (51.5) | 335 (48.4) | 92 (67.2) |
| Race and/or ethnicity, n (%) | |||
| African American | 131 (15.8) | 117 (16.9) | 14 (10.2) |
| Hispanic | 36 (4.3) | 33 (4.8) | 3 (2.2) |
| Asian American | 22 (2.7) | 21 (3.0) | 1 (0.7) |
| White | 532 (64.3) | 428 (61.9) | 104 (75.9) |
| Other | 107 (12.9) | 92 (13.3) | 15 (10.9) |
| Season at early adolescent visit, n (%) | |||
| Winter | 170 (20.5) | 140 (20.2) | 30 (21.9) |
| Spring | 222 (26.8) | 187 (27.0) | 35 (25.5) |
| Summer | 275 (33.2) | 229 (33.1) | 46 (33.6) |
| Fall | 162 (19.5) | 136 (19.7) | 26 (19.0) |
| Tanner stage,a mean (SD) | 3.6 (1.0) | 3.6 (1.0) | 3.5 (1.1) |
| Age, y, mean (SD) | 13.2 (0.9) | 13.2 (0.9) | 13.1 (0.8) |
| Television viewing, h per d, mean (SD) | 2.0 (1.4) | 2.1 (1.4) | 1.7 (1.1) |
| Fast food intake, servings per wk, mean (SD) | 0.7 (1.1) | 0.7 (1.1) | 0.6 (1.1) |
| Sugar sweetened beverage intake, servings per d, mean (SD) | 0.8 (0.9) | 0.8 (0.9) | 0.7 (0.7) |
| BMI z score, mean (SD) | 0.36 (1.07) | 0.41 (1.06) | 0.11 (1.07) |
| Actigraphy measurements, median (IQR) | |||
| Average daily MVPA, min | 7.0 (17.0) | 7.0 (16.0) | 7.0 (16.5) |
| Average daily sleep duration, min | 441.1 (54.8) | 432.7 (46.0) | 495.8 (21.9) |
| Average daily sleep efficiency, % | 84.0 (6.3) | 83.5 (6.1) | 86.3 (4.9) |
| Average daily WASO, min | 74.8 (36.2) | 75.9 (36.3) | 69.2 (33.9) |
| Day-to-day variability in sleep duration, SDb | 56.0 (35.4) | 55.7 (35.8) | 58.5 (34.1) |
| Adiposity outcomes, mean (SD) | |||
| BMI z score, n = 827 | 0.36 (1.07) | 0.41 (1.06) | 0.11 (1.07) |
| Waist circumference, cm, n = 829 | 72.8 (11.7) | 73.4 (11.9) | 69.7 (10.5) |
| Sum of skinfolds, mm, n = 826 | 28.2 (13.7) | 28.6 (14.2) | 26.2 (11.2) |
| DXA fat mass index, kg/m2, n = 619 | 6.3 (3.1) | 6.4 (3.2) | 5.9 (2.3) |
| DXA trunk fat mass index, kg/m2, n = 619 | 2.4 (1.5) | 2.4 (1.5) | 2.2 (1.1) |
| Cardiometabolic outcomes, mean (SD) | |||
| Metabolic risk, z score,c n = 493 | −0.02 (0.60) | 0.00 (0.61) | −0.12 (0.56) |
| HOMA-IR, n = 496 | 3.1 (1.9) | 3.2 (2.0) | 2.8 (1.4) |
| Insulin, μU/mL, n = 560 | 15.9 (14.9) | 16.4 (15.9) | 12.9 (6.1) |
| Glucose, mg/dL, n = 513 | 92.7 (23.5) | 93.0 (25.1) | 91.1 (11.5) |
| Systolic BP, mm Hg, n = 823 | 107.2 (8.9) | 107.7 (8.9) | 104.9 (9.0) |
| Triglycerides, mg/dL, n = 559 | 69.8 (31.3) | 69.1 (31.3) | 73.4 (31.3) |
| HDL cholesterol, mg/dL, n = 560 | 55.3 (13.1) | 55.1 (13.2) | 56.9 (12.5) |
Data from 829 participants from Project Viva. BP, blood pressure.
a
Tanner stage pubic hair (5-point scale).
b
SD of daily time spent asleep (all days), minutes.
c
Mean of 5 sex- and cohort-specific z scores for waist circumference, systolic blood pressure, HDL cholesterol scaled inversely, and log-transformed triglycerides and HOMA-IR; higher scores are indicative of greater metabolic risk.