TABLE 1.

Demographics, Sleep Duration, and Anthropometric Data by Study Wave

	Wave 1	Wave 2	Wave 3	Wave 4	Wave 5	Wave 6	Wave 7	Wave 8
Sample size	1336	1261	1067	1076	1019	1045	971	1089
Age, mean (SD), y	14.3 (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 (%)
Female	666 (50.0)	631 (50.1)	544 (51.1)	542 (50.4)	520 (51.1)	531 (50.9)	446 (46.0)	562 (51.7)
Male	667 (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 (%)
Black	187 (14.0)	169 (13.4)	138 (12.9)	138 (12.8)	123 (12.1)	131 (12.5)	128 (13.2)	135 (12.4)
White	996 (74.6)	958 (76.0)	805 (75.5)	812 (75.5)	765 (75.1)	789 (75.5)	737 (75.9)	823 (75.6)
Other	153 (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 greater	936 (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 education	387 (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
Male	8.13 (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)
Female	8.16 (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
Male	1.69 (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)
Female	1.61 (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
Male	63.9 (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)
Female	56.6 (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)
Male	22.2 (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)
Female	21.7 (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)