TABLE 2

Adjusted Mean Values of T2D and Cardiovascular Risk Markers and Difference in Risk Markers Per Hour Increase in Sleep

Adjusted Means (95% CI)
Hours of Self-reported Sleep on a School Night
<9 h9–9.9 h10–10.9 h11–11.9 h≥12 hDifference per h of Sleep (95% CI)aPb
Body size27984120141166225
 Height (cm)140.1 (139.3 to 140.9)141.0 (140.6 to 141.5)140.2 (139.9 to 140.5)140.0 (139.6 to 140.4)139.0 (138.2 to 139.9)−0.26 (−0.44 to −0.08).005
 Weight (kg)37.8 (36.7 to 38.9)38.2 (37.6 to 38.8)37.2 (36.8 to 37.6)36.5 (36.0 to 37.0)35.4 (34.2 to 36.6)−0.51 (−0.76 to −0.26)<.0001
 BMI19.1 (18.7 to 19.5)19.0 (18.8 to 19.3)18.7 (18.6 to 18.9)18.4 (18.2 to 18.6)18.2 (17.7 to 18.6)−0.19 (−0.28 to −0.09)<.0001
 Sum skinfolds (mm)c42.0 (39.6 to 44.5)42.8 (41.3 to 44.2)41.2 (40.3 to 42.1)39.9 (38.8 to 41.1)38.8 (36.4 to 41.3)−1.79 (−3.08 to −0.49).007
 Fat mass (kg)12.6 (12.0 to 13.3)12.7 (12.3 to 13.1)12.3 (12.0 to 12.5)11.8 (11.5 to 12.2)11.2 (10.5 to 12.0)−0.27 (−0.42 to −0.11).001
 Fat-free mass (kg)25.2 (24.7 to 25.7)25.5 (25.2 to 25.8)25.0 (24.8 to 25.2)24.7 (24.5 to 24.9)24.2 (23.7 to 24.8)−0.24 (−0.35 to −0.13)<.0001
 Fat mass index (kg/m5)2.29 (2.19 to 2.39)2.21 (2.15 to 2.27)2.21 (2.17 to 2.26)2.15 (2.10 to 2.20)2.13 (2.02 to 2.24)−0.03 (−0.05 to 0.00).03
 Fat-free mass index (kg/m3)9.11 (9.01 to 9.22)9.06 (8.99 to 9.12)9.01 (8.96 to 9.06)8.95 (8.89 to 9.01)8.97 (8.86 to 9.09)−0.04 (−0.06 to −0.01).002
Cardiometabolic risk markers
 Insulin (mU/L)c,d7.68 (7.12 to 8.29)7.57 (7.22 to 7.93)7.42 (7.17 to 7.69)7.12 (6.83 to 7.43)6.42 (5.90 to 6.98)−2.88 (−4.50 to −1.23).001
 Insulin resistancec,d0.97 (0.90 to 1.04)0.95 (0.91 to 1.00)0.93 (0.90 to 0.97)0.90 (0.86 to 0.94)0.81 (0.75 to 0.88)−2.81 (−4.41 to −1.17).001
 Glucose (mmol/L)c4.55 (4.50 to 4.59)4.53 (4.50 to 4.56)4.52 (4.50 to 4.54)4.49 (4.47 to 4.52)4.53 (4.48 to 4.57)−0.24 (−0.44 to −0.03).03
 HbA1c (%)5.27 (5.23 to 5.31)5.26 (5.24 to 5.29)5.25 (5.23 to 5.26)5.24 (5.22 to 5.26)5.24 (5.20 to 5.28)−0.01 (−0.02 to 0.00).11
 HbA1c (mmol/mol)34 (34 to 35)34 (34 to 34)34 (34 to 34)34 (34 to 34)34 (34 to 34).11
 Leptin (ng/mL)c,d9.2 (8.2 to 10.3)9.7 (9.1 to 10.4)9.5 (9.1 to 9.9)8.6 (8.1 to 9.1)8.0 (7.1 to 9.0)−3.03 (−5.42 to −0.59).02
 Total cholesterol (mmol/L)4.6 (4.5 to 4.7)4.6 (4.5 to 4.6)4.6 (4.5 to 4.6)4.6 (4.5 to 4.6)4.5 (4.4 to 4.6)−0.01 (−0.03 to 0.01).32
 LDL cholesterol (mmol/L)2.7 (2.6 to 2.8)2.7 (2.6 to 2.7)2.7 (2.6 to 2.7)2.7 (2.7 to 2.7)2.7 (2.6 to 2.8)−0.01 (−0.02 to 0.01).57
 HDL cholesterol (mmol/L)1.5 (1.5 to 1.5)1.5 (1.5 to 1.5)1.5 (1.5 to 1.5)1.5 (1.5 to 1.5)1.5 (1.5 to 1.5)0.00 (−0.01 to 0.01).70
 Triglyceride (mmol/L)c0.8 (0.8 to 0.8)0.8 (0.8 to 0.8)0.8 (0.8 to 0.8)0.8 (0.8 to 0.8)0.8 (0.7 to 0.8)−0.35 (−1.37 to 0.67).50
 Urate (mmol/L)c0.2 (0.2 to 0.2)0.2 (0.2 to 0.2)0.2 (0.2 to 0.2)0.2 (0.2 to 0.2)0.2 (0.2 to 0.2)0.20 (−0.48 to 0.89).56
 Systolic BP (mm Hg)104.1 (102.9 to 105.4)105.1 (104.3 to 105.8)104.9 (104.4 to 105.4)104.5 (103.8 to 105.1)104.3 (102.9 to 105.7)0.03 (−0.25 to 0.31).84
 Diastolic BP (mm Hg)62.9 (61.8 to 64.1)63.5 (62.8 to 64.2)63.0 (62.4 to 63.5)62.8 (62.2 to 63.4)62.4 (61.2 to 63.6)0.00 (−0.25 to 0.25).97
  • Means of outcome variables by sleep category from multilevel model are adjusted for sex, age quartile, month, ethnicity, social position, observer (physical measures only), and random effect for school.

  • HDL, high-density lipoprotein; LDL, low-density lipoprotein.

  • a Regression coefficients from the multilevel model for continuous association with hours of sleep are adjusted for sex, age quartile, month, ethnicity, social position, observer (physical measures only), and random effect for school. For log-transformed outcomes, these represent percent differences.

  • b P values for regression coefficients from the multilevel model assume a linear continuous association with sleep duration.

  • c Geometric means for log-transformed variables.

  • d Insulin and insulin resistance data are missing for 76 children; leptin data are missing for 97 children.