TABLE 1

Demographics, Sleep Duration, and Anthropometric Data by Study Wave

Wave 1Wave 2Wave 3Wave 4Wave 5Wave 6Wave 7Wave 8
Sample size1336126110671076101910459711089
Age, mean (SD), y14.3 (0.56)14.8 (0.59)15.3 (0.53)15.7 (0.55)16.3 (0.55)16.8 (0.55)17.3 (0.54)17.7 (0.56)
Gender, n (%)
 Female666 (50.0)631 (50.1)544 (51.1)542 (50.4)520 (51.1)531 (50.9)446 (46.0)562 (51.7)
 Male667 (50.0)629 (49.9)521 (48.9)533 (49.6)498 (48.9)513 (49.1)523 (54.0)525 (48.3)
Race, n (%)
 Black187 (14.0)169 (13.4)138 (12.9)138 (12.8)123 (12.1)131 (12.5)128 (13.2)135 (12.4)
 White996 (74.6)958 (76.0)805 (75.5)812 (75.5)765 (75.1)789 (75.5)737 (75.9)823 (75.6)
 Other153 (11.5)134 (10.6)124 (11.6)126 (11.7)131 (12.9)125 (12.0)106 (10.9)131 (12.0)
Maternal education, n (%)
 High school education or greater936 (70.8)880 (70.6)765 (72.6)765 (72.0)719 (71.2)730 (70.6)686 (71.5)764 (70.9)
 Less than high school education387 (29.3)367 (29.4)289 (27.4)298 (28.0)288 (28.6)304 (29.4)273 (28.5)314 (29.1)
Sleep, mean (SD), hr/d
 Male8.13 (1.69)8.01 (1.75)7.93 (1.75)7.94 (1.62)7.93 (1.70)7.82 (1.58)7.72 (1.51)7.54 (1.61)
 Female8.16 (1.68)7.98 (1.75)7.95 (1.65)7.82 (1.64)7.69 (1.64)7.67 (1.59)7.65 (1.55)7.52 (1.59)
Height, mean (SD), m
 Male1.69 (0.09)1.72 (0.08)1.73 (0.08)1.74 (0.08)1.75 (0.08)1.76 (0.08)1.76 (0.08)1.76 (0.08)
 Female1.61 (0.07)1.62 (0.07)1.62 (0.07)1.63 (0.07)1.63 (0.08)1.63 (0.07)1.64 (0.07)1.63 (0.07)
Wt, mean (SD), kg
 Male63.9 (13.9)67.0 (14.3)68.7 (13.7)69.9 (13.8)71.9 (14.5)73.4 (14.5)74.7 (14.6)75.3 (14.5)
 Female56.6 (10.4)58.2 (10.9)58.2 (10.2)58.8 (10.3)60.0 (11.1)60.8 (10.9)64.4 (10.6)61.4 (11.0)
BMI, mean (SD)
 Male22.2 (4.04)22.6 (4.11)22.9 (4.02)23.0 (4.08)23.3 (4.22)23.6 (4.20)24.0 (4.39)24.1 (4.28)
 Female21.7 (3.67)22.1 (3.85)22.0 (3.44)22.1 (3.47)22.5 (3.66)22.8 (3.70)23.9 (3.87)23.0 (3.73)