The Effects of Genetic Background for Diurnal Preference on Sleep Development in Early Childhood

Figures & data

Table 1 Socio-Demographic Factors and Variables of Interest in CHILD-SLEEP and FinnBrain

	CHILD-SLEEP Cohort*	Finnbrain Cohort*
	Mean (SD)	Mean (SD)
PRSBestFit	−0.0001 (0.996)	−0.0011 (1.001)
PRS10kBest	0.0025 (1.002)	0.0006 (1.000)
Age (in days)
At 3 months	99.12 (15.09)	–
At 6 months	–	196.18 (10.42)
At 8 months	247.73 (11.60)	–
At 12 months	–	380.45 (14.79)
At 18 months	558.00 (50.97)	–
At 24 months	752.10 (42.54)	747.67 (19.98)
Nighttime sleep hours
At 3 months	9.11 (1.42)	–
At 6 months	–	9.95 (1.28)
At 8 months	9.88 (0.99)	–
At 12 months	–	10.29 (0.94)
At 18 months	10.22 (0.81)	–
At 24 months	9.99 (0.77)	–
Daytime sleep hours
At 3 months	5.20 (1.47)	–
At 6 months	–	3.78 (1.28)
At 8 months	3.44 (1.94)	–
At 12 months	–	2.55 (0.91)
At 18 months	2.09 (0.68)	–
At 24 months	1.88 (0.67)	–
Sleep latency, min
At 3 months	37.02 (31.57)	–
At 6 months	–	41.66 (32.25)
At 8 months	22.29 (16.11)	–
At 12 months	–	34.79 (28.86)
At 18 months	19.78 (14.44)	–
At 24 months	25.18 (19.43)	23.95 (10.38)
Bedtime, hh:mm
At 3 months	21:46 (1:12)	–
At 6 months	–	20:53 (0:58)
At 8 months	20:48 (1:27)	–
At 12 months	–	20:37 (0:49)
At 18 months	20:42 (0:42)	–
At 24 months	20:55 (0.40)	20:42 (0:40)

Note: *CHILD-SLEEP cohort sample in this study comprised 695 girls (47.2%) and 778 boys (52.8); and FinnBrain cohort sample 962 girls (47.0%) and 1083 boys (53.0%).

Abbreviations: PRS_BestFit, polygenetic risk score for eveningness; PRS_10kBest, polygenetic risk score for morningness.

Table 2 Associations Between Genetic Risk for Diurnal Preference and Mean Standard Scores for Each Sleep Domain, in CHILD-SLEEP

CHILD-SLEEP Cohort		PRSBESTFIT			PRS10KBEST
Sleep Domains	N	R^2	β	p	R^2	β	p
Night sleep duration	1262	0.011	−0.033	0.253	0.012	0.035	0.210
Daytime sleep duration	1262	0.008	0.053	0.109	0.005	−0.081	0.936
ISQ Sleep-onset latency	1262	0.019	0.081	0.004**	0.016	−0.060	0.034
BISQ Sleep-onset latency	1262	0.020	0.081	0.004**	0.016	−0.045	0.115
Bedtime	1262	0.028	0.085	0.003**	0.021	0.005	0.851

Notes: Bold indicates statistically significant associations (p < 0.05). **After FDR correction, the associations between PRS_BestFit and ISQ and BISQ sleep-onset latency and bedtime remained significant (FDR<0.005).

Abbreviations: ISQ, Infant Sleep Questionnaire; BISQ, Brief Infant Sleep Questionnaire; PRS_BestFit, polygenic risk score for eveningness; PRS_10kBest, polygenic risk score for morningness.

Figure 1 Sleep-onset latency and genetic risk for diurnal preference in early childhood. This graph presents the mean and standard error (SE) in parent-reported sleep-onset latency in early childhood, for each quartile of PRS_BestFit (A) and PRS_10kBest (B), in the CHILD-SLEEP cohort. The measure of parent-reported sleep-onset latency in childhood refers to mean standard scores at three, eight, 18 and 24 months, from the Infant Sleep Questionnaire. Graph A indicates that those subjects situated in the 4th Quartile (ie higher PRS for eveningness) report higher mean standard score values in ISQ sleep-onset latency (ie longer sleep-onset latency). Accordingly, graph B shows that those infants located in the 4th Quartile (ie higher PRS for morningness) obtain lower mean standard values in ISQ sleep-onset latency (ie short sleep-onset latency). Error bars represent 2SE, indicating 95% of values that are less than two standard errors (2SE) away from the mean.

Figure 2 Forest plot from the meta-analysis, concerning genetic risk for diurnal preference and sleep-onset latency in early childhood. This graph provides a graphical display of the estimated results when we combined the data from both cohorts (CS and FB) to perform meta-analysis. Graph (A) represents the forest plot from the meta-analysis, concerning the association between PRS_BestFit and sleep-onset latency in early childhood. Graph (B) represents the forest plot from the meta-analysis, concerning the association between PRS_10kBest and sleep-onset latency in early childhood. First dark blue square on the top, in each graph, represents the standard mean differences (and 95% Confidence Intervals) for sleep-onset latency measured with Infant Sleep Questionnaire in CS, and the dark blue square below, in each graph, refers to the standard mean differences (and 95% Confidence Intervals) for sleep-onset latency measured with Brief Infant Sleep Questionnaire in FB. The light blue diamond on the bottom appearing in each graph represents the overall effect estimate.

Abbreviations: SMD, standardized mean difference; CI, confidence interval; CS, CHILD-SLEEP; FB, FinnBrain; ISQ, Infant Sleep Questionnaire; BISQ, Brief Infant Sleep Questionnaire; PRSBestFit, polygenic risk score for eveningness; PRS10kBest, polygenic risk score for morningness.

Table 3 Associations Between Genetic Risk for Diurnal Preference and Actigraphy-Based Sleep Variables, in CHILD-SLEEP

			PRSBestFit			PRS10kBest
	Time Point	N	R^2	β	p	R^2	β	p
Night sleep efficiency	Mean standard scores	320	0.054	−0.150	0.008	0.036	0.058	0.307
	8 months	300	0.055	−0.154	0.008	0.035	0.049	0.399
	24 months	131	0.049	−0.035	0.698	0.052	−0.068	0.459
Night sleep latency	Mean standard scores	300	0.018	0.062	0.280	0.015	−0.018	0.752
	8 months	320	0.045	0.116	0.046	0.032	0.009	0.874
	24 months	131	0.049	−0.140	0.127	0.032	0.042	0.652

Note: Bold indicates statistically significant associations (p < 0.05).

Abbreviations: PRS_BestFit, polygenic risk score for eveningness; PRS_10kBest, polygenic risk score for morningness.