0-1 year

(N = 54)

1-2 years

(N = 330)

2-4 years

(N = 880)

Sleep onset

Within 20 minutes

30 (55.6%)

184 (55.8%)

390 (44.3%)

More than 20 minutes

24 (44.4%)

146 (44.2%)

490 (55.7%)

Child’s sleep duration

Less than 10 hours

29 (53.7%)

128 (38.8%)

323 (36.7%)

10-12 hours

18 (33.3%)

159 (48.2%)

479 (54.4%)

12-14 hours

3 (05.6%)

37 (11.2%)

71 (08.1%)

More than 14 hours

4 (07.4%)

6 (01.8%)

7 (00.8%)

Child’s sleep time

8:00 pm

17 (31.5%)

55 (16.7%)

112 (12.7%)

at 10 or 11 pm

27 (50.0%)

173 (52.4%)

506 (57.5%)

at 12 or later

10 (18.5%)

102 (30.9%)

262 (29.8%)

Parent’s sleep time

8:00 pm

5 (09.3%)

3 (00.9%)

14 (01.6%)

at 10 or 11 pm

21 (38.9%)

113 (34.2%)

310 (35.2%)

at 12 or later

28 (51.9%)

214 (64.8%)

556 (63.2%)

Sibling’s sleep time

8:00 pm

10 (18.5%)

58 (17.6%)

123 (14.0%)

at 10 or 11 pm

33 (61.1%)

179 (54.2%)

520 (59.1%)

at 12 or later

11 (20.4%)

93 (28.2%)

237 (26.9%)