Fig. 2

Differences in total quality of life among sleep duration, age, gender, and education level. (A), sleep duration, below 9 h (sleep deprivation, SDT) and 9 h and above (adequate sleep, AS); (B), age; (C), gender; (D), education level. **, p-value is less than 0.01; ****, p-value is less than 0.0001. “a” indicates that there is no statistically significant difference in the results