Table 1.

Characteristics of study participants, classified by sleep duration (unweighted)

	Total	Hours of sleep per day					p-value
		≤5	6	7–8	9	≥10
# of participants	13,441	1,588	1,826	4,877	1,133	4,017	NA
% participant across sleep hours	100.0	11.81	13.59	36.28	8.43	29.89	NA
% Death in 2008–2014	58.4	57.0	52.8	51.2	56.0	70.8	< 0.001
Frequency of vegetable consumption
% High	87.6	83.6	88.5	89.4	89.8	86.4	< 0.001
Demographics
Age (mean, years)	87.0	86.2	85.0	85.0	86.0	91.1	< 0.001
% Aged over 80 years	73.1	72.7	67.1	65.8	70.8	85.7	< 0.001
% Male	42.9	37.8	42.5	44.7	49.8	41.1	< 0.001
% Urban	36.7	34.8	39.3	37.4	35.7	35.8	0.027
Socioeconomic factors
% 0 years of schooling	63.5	66.9	59.2	59.6	60.8	70.0	< 0.001
% Economic independence	25.8	25.1	31.1	30.7	26.0	17.8	< 0.001
% Professional occupation	9.4	8.2	10.5	10.9	7.9	8.0	< 0.001
% Access to healthcare	92.4	86.7	90.4	92.8	95.0	94.5	< 0.001
Family/Social support
% Married	32.7	32.0	37.0	38.2	36.8	23.3	< 0.001
% Close proximity to children	87.3	84.3	86.9	87.1	88.1	88.7	< 0.001
Health practice
% Doing regular exercise	27.3	28.1	30.2	30.7	28.9	28.3	< 0.001
% Currently smoking	17.9	16.9	19.4	18.6	18.8	16.5	0.016
Health condition
% ADL disabled	20.6	21.5	18.4	14.3	13.0	31.2	< 0.001
% Cognitively impaired	44.3	42.2	39.9	36.5	36.9	58.6	< 0.001
% Self-reported poor health	51.1	67.9	59.1	47.9	44.2	46.6	< 0.001

Note: (1) NA not applicable. (2) Age was measured in mean, whereas all other variables were measured in percentage. (3) Except for the total sample whose unweighted proportion was calculated across sleep hours, unweighted percentages for all other variables were calculated within each sleep hour group. (4) Except for the variable death, all other variables were measured at baseline wave in 2008. (5) p values were based on chi-square tests (for categorical variables) except for mean age that was derived from analysis of variance