Table 1.

Weighted Means and Percentages of Covariates by Self-reported Sleep Hours in a Usual 24-Hour Period, US Adults Aged 18 Years or Older, 2004–2007^a

	Self-reported Sleep Hours					P Valueb
	≤5	6	7	8	≥9
Total, %	7.8	20.5	30.8	32.5	8.5
Demographic status
Age, mean years	46.8	45.4	45.2	46.2	49.7	<0.001
Sex, %						<0.001
Female	7.9	19.9	29.8	33.3	9.2
Male	7.6	21.1	31.9	31.6	7.8
Race/ethnicity, %						<0.001
Non-Hispanic white	7.4	20.1	32.1	32.1	8.3
Non-Hispanic black	11.0	23.8	25.0	30.2	10.1
Other non-Hispanic	7.9	22.1	31.3	31.5	7.2
Mexican American	5.4	17.1	27.9	40.1	9.5
Other Hispanic	9.0	21.2	31.0	32.3	6.6
Foreign born, %						<0.001
No	8.0	20.7	30.7	31.9	8.7
Yes	6.6	19.2	31.3	35.8	7.2
Family structure
Any children, %						<0.001
No children	7.4	19.2	29.7	34.0	9.8
>0–<2 years	9.2	25.1	31.2	28.3	6.2
2–<6 years	8.2	22.9	32.5	30.2	6.2
6–<13 years	8.5	22.7	33.8	29.3	5.8
13–<18 years	9.2	23.3	33.8	28.8	4.9
Currently pregnant, %						<0.001
No	7.8	20.6	30.9	32.4	8.4
Yes	4.1	11.4	21.4	42.6	20.6
Currently married, %						<0.001
No	8.8	20.8	28.2	32.1	10.2
Yes	7.0	20.2	32.8	32.8	7.2
Socioeconomic status
Hours worked per week, %						<0.001
≥41	9.7	27.0	35.6	24.4	3.3
35–40	6.3	21.2	35.2	32.6	4.7
1–34	6.9	18.9	30.4	35.0	8.9
Not working	8.5	16.7	23.9	35.9	15.0
Education, %						<0.001
Less than high school degree	10.1	19.0	23.8	34.2	12.9
High school degree	7.7	20.1	28.5	34.2	9.6
Some college	8.6	22.0	31.0	30.8	7.6
College degree or higher	5.1	20.2	38.2	31.4	5.1
Family income, mean $	36,819	43,869	48,065	42,907	34,883	<0.001
Family income portfolio, mean score	1.01	1.11	1.20	1.15	1.15	<0.001
Health behaviors
Physical activity index, mean	−0.01	0.05	0.12	0.02	−0.15	<0.001
Smoking status						<0.001
Current smoker, mean packs smoked/day	0.25	0.17	0.12	0.12	0.16
Former smoker, %	7.2	20.5	30.5	32.0	9.9
Never smoker, %	6.6	19.5	32.3	34.0	7.6
Drinks consumed last week, mean	2.72	2.53	2.38	2.27	2.37	0.042
Days binge drank last year, mean	10.6	8.5	6.9	7.0	8.5	0.005
Health status
Cardiovascular disease, %						<0.001
No	6.6	20.1	32.7	33.5	7.2
Yes	10.4	21.2	26.8	30.4	11.3
Acute respiratory condition, %						<0.001
No	7.1	20.0	31.4	33.2	8.3
Yes	11.7	22.9	27.2	28.7	9.6
Chronic respiratory condition, %						<0.001
No	7.2	20.2	31.4	33.1	8.2
Yes	12.3	22.2	26.8	28.1	10.6
Diabetes, %						<0.001
No	7.4	20.5	31.5	32.6	8.0
Yes	11.4	20.5	23.5	31.2	13.4
Pain, %						<0.001
No	5.2	18.5	32.5	35.7	8.0
Yes	11.9	23.7	28.0	27.2	9.3
Depression index, mean	0.5	0.0	−0.2	−0.2	0.3	<0.001
Anxiety index, mean	0.5	0.1	−0.1	−0.2	0.1	<0.001
Body mass, %						<0.001
Obese	10.6	23.5	28.1	29.0	8.9
Overweight	7.6	20.2	31.9	32.7	7.8
Normal weight	6.1	18.8	32.1	34.5	8.6
Underweight	7.7	17.7	23.5	36.7	14.5
Activity limitations, %						<0.001
No	6.6	20.8	32.9	33.2	6.6
Yes	14.2	18.8	19.2	28.8	19.1

^aUnweighted N = 110,441.

^bSignificant P values indicate that the distribution of a given covariate differs across sleep duration. The authors used Wald tests that account for the complex sampling frame used by the National Health Interview Survey.