Gender and age specific scores of sleep quality components measured by the Chinese version of the Pittsburgh Sleep Quality Index.

Mean differences analyzed with t tests or ANOVA; proportional differences analyzed with Pearson Chi-squared test or Cochran-Mantel-Haenszel Chi-squared test.
M, mean; SD, standard deviation.
☆Scores range from 0 to 3; higher scores indicate poor subjective sleep quality.
*Habitual sleep efficiency was derived from the formula: hours of sleep/(get-up time - usual bedtime) *100%.
★Derived from Pittsburgh Sleep Quality Index (PSQI) items 5b–5j; scores range from 0 to 3; higher scores indicate more sleep disturbances.
▾Derived from PSQI items 7–8; scores range from 0 to 3; higher scores indicate more daytime dysfunction.