this study on pre-schoolers N = 44

Hattori’s study on pre-schoolers N = 459

z

p

M

SD

M

SD

wake-up time

7:06

30 min

7:07

25 min

−1.579

0.114

bedtime

21:36

41 min

21:17

38 min

0.316

0.752

sleeping duration

9.5 hour

36 min

9.8 hour

45 min

1.769

0.077