Longitudinal Study of Infant Sleep Development: Early Predictors of Sleep Regulation Across the First Year

Figures & data

Figure 1 Longitudinal frequency distribution of Infant Composite Sleep Scores at 1, 3, 6, 9 and 12 months of age.

Table 1 Bivariate Associations Between 1-Month Infant and Parent Variable Means (SD), and Infant Sleep Status at 6 and 12 Months of Age

1-Month Variables	Self-Sleep Regulated Mean ± SD	Non-Self Sleep Regulated Mean ± SD	p	Cohen’s d (95% CI)
Group Status at 6 Months	N = 29	N = 23
Infant Behaviours
LSRSP (mins)	353.20 ± 94	293.22 ± 89.17	0.02	0.65 (0.09,1.21)
Night waking/6 nights	6.69 ± 2.75	10.22 ± 4.42	<0.001	−0.95 (−1.56, −0.40)
Total Sleep Time/24h	878.57 ± 133.59	801.44 ± 112.59	0.03	0.62 (0.05, 1.18)
Sleep/Wake Transitions/24h	5.17 ± 1.52	6.12 ± 1.56	0.03	−0.61 (−1.18, −0.05)
Parental Behaviours
Sleep Onset Rituals	3.20 ± 0.95	3.34 ± 1.09	0.62	−0.30 (−0.69, 0.41)
Night Waking Interventions	2.55 ± 0.95	3.39 ± 1.31	0.01	−0.73 (−1.3, −0.18)
Parental Presence/6 nights	1.96 ± 2.06	4.86 ± 1.48	<0.001	−1.61 (−2.21, −0.95)
Placed in Crib Asleep/6 nights	1.59 ± 1.57	4.00 ± 2.07	<0.001	−1.32 (−1.93, −0.72)
Bed Sharing/6 nights	0.10 ± 0.41	2.96 ± 2.50	<0.001	−1.72 (−2.33, −1.05)
Group Status at 12 Months	N = 37 Mean ± SD	N = 15 Mean ± SD
Infant Behaviours
LSRSP (mins)	343.40 ± 98.0	285.40 ± 79.93	0.04	0.65 (0.01, 1.23)
Nightwaking/6 nights	7.22 ± 3.35	10.80 ± 4.310	<0.001	−0.92 (−1.61, −0.35)
Total Sleep Time/24h	854.72 ± 123.09	819.13 ± 145.40	0.37	0.26 (−0.33, 0.88)
Sleep/Wake Transitions/24h	5.40 ± 1.56	6.06 ± 1.62	0.17	−0.56 (−1.02, - 0.19)
Parental Behaviours
Sleep Onset Rituals	3.19 ± 0.95	3.46 ± 1.16	0.38	−0.25 (−0.87, −0.34)
Night Waking Interventions	2.70 ± 1.10	3.47 ± 1.25	0.03	−0.65 (−1.28, −0.06)
Parental Presence/6 nights	2.43 ± 2.16	5.26 ± 1.2	<0.001	−1.34 (−2.18, −0.79)
Placed Crib Asleep/6 nights	2.05 ± 1.81	4.13 ± 2.29	<0.001	−0.98 (−1.69, −0.42)
Bed Sharing/6nights	0.56 ± 1.44	3.33 ± 2.53	<0.001	−1.41 (−2.19, −0.85)

Table 2 Comparison of Parental Settling Interventions at Age 1 month Between Parents of Self-Sleep-Regulated and Parents of Non-Self Sleep-Regulated Sleepers at 6 and 12-Months

1-Month Categorical Variable	6-Month Sleep Group Status					12-Month Sleep Group Status
	S-R (n=29)	NS-R (n=23)	OR	χ^2 (df)	P	S-R (n=37)	NS-R (n=15)	OR	χ^2 (df)	P
%Nights Parental Presence
≥80	2	14	44.33	20.50 (2)	<0.001	9	13	27.44	23.33 (2)	<0.001
50–79	8	6	4.75			9	1	2.11
<50	19	3				19	1
%Nights Placed in Crib Asleep
≥80	2	16	44.41	26.36 (2)	<0.001	7	11	28.29	14.85 (2)	<0.001
50–79	9	6	12			12	3	4.5
<50	18	1				18	1
Bed-sharing
Yes	2	11	12.38	11.46 (1)	<0.001	5	9	9.6	12.4 (1)	<0.001
No	27	12				32	6

Table 3 Classification Results for Predicted Sleep Group Status at A. Age 6 Months, and B. Age 12 Months

A		6-Month Group	Predicted Group Status			Total
			Self-Sleep Regulated	Non-Self Sleep Regulated
Original	Count	Sleep Regulated	28	1		29
		Non-Self- Regulated	2	21		23
	%	Sleep Regulated	96.6	3.4		100.0
		Non-Sleep-Regulated	8.7	91.3		100.0
B		12-Months Group	Predicted Group Status			Total
			Self-Sleep Regulated		Non-Self Sleep Regulated
Original	Count	Sleep Regulated	32		5	37
		Non-Sleep-Regulated	3		12	15
	%	Sleep Regulated	86.5		13.5	100.0
		Non-Sleep-Regulated	20.0		80.0	100.0

Notes: Classification Results: 94.2% of original grouped cases correctly classified. Classification Results: 84.6% of original grouped cases correctly classified.