TABLE 1.

Characteristics of the surveyed population by categories of weekday/workday duration of nighttime sleep reported by adult Americans: NHANES 2005–2010¹

			Categories of sleep duration
	n	All (n = 15,199)	≤6 h (n = 5994)	7–8 h (n = 8053)	≥9 h (n = 1152)
All	15,199	—	36.4 ± 0.8	56.1 ± 0.7	7.5 ± 0.3
Sex
Men	7601	48.6 ± 0.4	51.0 ± 0.9	48.5 ± 0.6	37.8 ± 2.1
Women	7598	51.4 ± 0.4	49.0 ± 0.9	51.5 ± 0.6	62.2 ± 2.1
Age
20–39 y	4950	36.4 ± 0.8	36.9 ± 1.1	36.0 ± 0.9	37.9 ± 2.5
40–59 y	5015	38.9 ± 0.6	41.8 ± 0.9	38.4 ± 0.8	28.0 ± 2.1
60–69 y	2458	12.7 ± 0.4	11.2 ± 0.5	13.7 ± 0.6	12.4 ± 1.3
≥70 y	2776	12.0 ± 0.5	10.0 ± 0.5	11.9 ± 0.6	21.7 ± 1.8
Race-ethnicity
Non-Hispanic white	7408	70.8 ± 1.9	64.7 ± 2.3	74.4 ± 1.8	73.2 ± 2.6
Non-Hispanic black	3089	11.3 ± 1.0	16.7 ± 1.5	7.9 ± 0.7	10.8 ± 1.4
Mexican American	2740	8.1 ± 0.9	7.6 ± 0.9	8.4 ± 0.9	8.0 ± 1.5
Other	1962	9.8 ± 0.8	10.9 ± 0.9	9.3 ± 0.9	8.0 ± 1.1
Poverty-income ratio
≤1.3	4212	19.1 ± 0.8	21.8 ± 1.0	16.5 ± 0.7	25.0 ± 2.0
>1.3–3.5	5434	33.6 ± 0.9	34.7 ± 1.0	32.3 ± 1.1	38.2 ± 2.4
>3.5	4376	41.2 ± 1.2	36.4 ± 1.3	45.5 ± 1.3	32.0 ± 2.5
Unknown	1177	6.11 ± 0.4	7.0 ± 0.6	5.7 ± 0.4	4.8 ± 0.8
Education
<12 y	4388	18.6 ± 0.8	19.7 ± 0.8	16.8 ± 0.9	26.5 ± 2.1
12 y	3641	24.6 ± 0.7	26.9 ± 1.0	23.1 ± 0.9	24.4 ± 1.5
Some college	4165	30.6 ± 0.5	33.9 ± 1.0	28.7 ± 0.8	28.4 ± 2.0
College	2987	25.2 ± 1.1	19.4 ± 0.9	31.3 ± 1.5	20.6 ± 2.0
Employment
Yes	8449	63.0 ± 0.8	64.8 ± 0.9	65.0 ± 1.0	39.0 ± 2.1
No	6748	37.0 ± 0.8	35.2 ± 0.9	35.0 ± 1.0	61.0 ± 2.1
Smoking status
Never smoked	7992	52.4 ± 0.9	48.4 ± 1.1	54.9 ± 1.1	53.3 ± 2.1
Former smoker	3835	24.5 ± 0.6	22.6 ± 0.7	26.1 ± 0.9	20.9 ± 1.7
Current smoker	3368	23.1 ± 0.7	28.9 ± 0.9	18.9 ± 0.7	25.7 ± 2.0
Alcohol drinking status
Never drinker	1898	10.1 ± 0.6	9.8 ± 0.7	9.7 ± 0.6	15.1 ± 1.8
Former drinker	2125	12.2 ± 0.5	12.9 ± 0.7	11.7 ± 0.6	12.0 ± 1.2
Current drinker	10,130	71.2 ± 0.9	70.4 ± 1.1	72.2 ± 1.0	66.9 ± 2.4
Unknown	1046	6.5 ± 0.4	6.9 ± 0.6	6.4 ± 0.5	6.0 ± 0.8
Any current self-reported  chronic disease?
Yes	6935	40.4 ± 0.8	45.3 ± 0.9	36.9 ± 1.0	43.1 ± 2.1
No	8264	59.6 ± 0.8	54.7 ± 0.9	63.1 ± 1.0	56.9 ± 2.1
BMI
<25 kg/m2	4327	31.4 ± 0.8	28.4 ± 0.8	32.5 ± 1.0	38.0 ± 2.1
25 to <30 kg/m2	5141	33.2 ± 0.6	32.7 ± 0.9	34.2 ± 0.9	28.0 ± 1.7
≥30 kg/m2	5545	34.4 ± 0.7	37.9 ± 0.8	32.4 ± 1.0	31.6 ± 2.2
Day of recalled intake
Monday–Thursday	5795	57.1 ± 0.6	55.5 ± 1.1	57.0 ± 0.9	64.9 ± 1.7
Friday–Sunday	9404	42.9 ± 0.6	44.5 ± 1.1	43.0 ± 0.9	35.1 ± 1.7
Month of MEC examination
November–April	6883	39.8 ± 3.4	40.6 ± 3.5	38.8 ± 3.4	44.2 ± 4.2
May–October	8316	60.1 ± 3.4	59.4 ± 3.5	61.2 ± 3.4	55.9 ± 4.2
Physical activity level (MET-min/wk)2  (NHANES 2007–2010 only)	11,041
First tertile	4249	32.2 ± 1.2	31.6 ± 1.2	31.3 ± 1.2	43.5 ± 2.3
Second tertile	3486	34.7 ± 0.7	31.2 ± 0.8	37.2 ± 0.9	32.4 ± 2.1
Third tertile	3304	33.1 ± 0.8	37.2 ± 1.0	31.6 ± 1.1	24.0 ± 1.8

¹All values are weighted percentages ± SEs unless otherwise indicated. MEC, mobile examination center; MET-min, metabolic equivalent task-minutes.

²Computed from minutes per week of self-reported work-, transportation-, household-, and recreation-related physical activity.