Table 1.

Population characteristic according to hours of day napping and night sleeping

	Day napping			Night sleeping
	None	<1 h	≥1 h	<5 h	5–6 h	7–8 h	≥9 h
n*	94,165	67,520	12,335	3,963	53,030	111,731	5,620
Age (years)	61.6 ± 5.3	63.4 ± 5.2	63.5 ± 5.3	62.2 ± 5.4	62.1 ± 5.4	62.6 ± 5.3	63.3 ± 5.2
Men (%)	51.3	63.2	64.4	47.8	55.1	58.0	55.9
Whites (%)	95.3	94.7	90.3	87.6	92.0	96.1	96.6
High school or more (%)	81.3	78.8	74.2	67.1	77.1	81.5	80.3
Married or couples (%)	68.3	72.8	68.2	57.3	66.3	72.3	70.5
Past smokers (%)	49.9	51.8	51.8	45.7	49.7	51.4	52.9
Current smokers (%)	8.9	9.3	15.9	13.1	10.8	8.9	9.0
≥2 cups of coffee/day (%)	57.6	56.8	55.4	51.7	56.8	57.7	53.0
≥1 drink of alcohol/day (%)	26.3	23.6	21.4	18.2	21.4	26.3	34.2
Health status (%)
Excellent or very good	66.6	58.2	45.3	42.9	58.1	64.5	57.3
Good	28.3	33.9	39.3	36.9	33.8	29.8	31.5
Fair or poor	5.1	7.9	15.4	20.2	8.1	5.7	11.2
BMI (kg/m2)	26.1 ± 4.5	26.8 ± 4.7	27.6 ± 5.3	27.8 ± 5.7	26.8 ± 5.1	26.2 ± 4.5	26.5 ± 4.8
≥ 4 h/week light activities (%)	62.4	62.7	58.6	58.3	60.1	63.4	62.3
≥4 h/week moderate to vigorous activities (%)	53.2	52.7	45.1	48.2	51.0	53.4	48.2
Calorie intake (kcal)	1,770 ± 789	1,872 ± 861	2,022 ± 1,025	1,981 ± 1,253	1,833 ± 891	1,814 ± 783	1,943 ± 1,005
Family history of diabetes (%)	24.4	26.2	27.9	29.7	26.8	24.6	24.3
Napping (%)
0				44.5	50.3	56.3	53.9
<1 h				38.6	40.8	38.2	32.7
≥1 h				16.9	8.8	5.6	13.4
Sleeping (%)
<5 h	1.9	2.3	5.4
5–6 h	28.3	32.0	38.0
7–8 h	66.6	63.0	50.5
≥9 h	3.2	2.7	6.1

Data are means ± SD for continuous variables and proportions for categorical variables. N = 174,344. Hours of day napping and night sleeping, age, physical activity, and family history of diabetes were from risk factor survey in 1996–1997; all other covariates were collected at the dietary survey in 1995–1996.

*The final number of participants for individual variables varies because of missing values.