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Table 1 Characteristics of study participants, classified by sleep duration (unweighted)

From: Sleep duration, vegetable consumption and all-cause mortality among older adults in China: a 6-year prospective study

  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
  1. 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