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Sleep and Cognition in Preschool Years: Specific Links to Executive Functioning

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Title: Sleep and Cognition in Preschool Years: Specific Links to Executive Functioning
Language: English
Authors: Bernier, Annie, Beauchamp, Miriam H., Bouvette-Turcot, Andrée-Anne, Carlson, Stephanie M., Carrier, Julie
Source: Child Development. Sep-Oct 2013 84(5):1542-1553.
Availability: Wiley-Blackwell. 350 Main Street, Malden, MA 02148. Tel: 800-835-6770; Tel: 781-388-8598; Fax: 781-388-8232; e-mail: cs-journals@wiley.com; Web site: http://www.wiley.com/WileyCDA/
Peer Reviewed: Y
Page Count: 12
Publication Date: 2013
Document Type: Journal Articles
Reports - Research
Descriptors: Sleep, Executive Function, Infants, Preschool Children, Cognitive Ability, Mothers
Assessment and Survey Identifiers: Wechsler Preschool and Primary Scale of Intelligence
DOI: 10.1111/cdev.12063
ISSN: 0009-3920
Abstract: This study investigated the prospective links between sleep in infancy and preschoolers' cognitive performance. Mothers of 65 infants completed a sleep diary when infants were aged 1 year, and children completed two subscales of the Wechsler Preschool and Primary Scale of Intelligence at 4 years, indexing general cognitive ability and complex executive functioning. Consistent with hypotheses, children getting higher proportions of their sleep at night as infants were found to perform better on executive functions, but did not show better general cognition. Relations held after controlling for family socioeconomic status and prior cognitive functioning. These findings suggest that the special importance of sleep for higher order cognition, documented among adults, may appear very early in life.
Abstractor: As Provided
Entry Date: 2014
Accession Number: EJ1025310
Database: ERIC
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  Value: <anid>AN0090064464;cdv01sep.13;2018Jul11.08:27;v2.2.500</anid> <title id="AN0090064464-1">Sleep and Cognition in Preschool Years: Specific Links to Executive Functioning. </title> <p>This study investigated the prospective links between sleep in infancy and preschoolers' cognitive performance. Mothers of 65 infants completed a sleep diary when infants were aged 1 year, and children completed two subscales of the Wechsler Preschool and Primary Scale of Intelligence at 4 years, indexing general cognitive ability and complex executive functioning. Consistent with hypotheses, children getting higher proportions of their sleep at night as infants were found to perform better on executive functions, but did not show better general cognition. Relations held after controlling for family socioeconomic status and prior cognitive functioning. These findings suggest that the special importance of sleep for higher order cognition, documented among adults, may appear very early in life.</p> <p>Cognitive performance is one of the aspects of human functioning that shows the clearest connections to sleep among adults (Walker, [<reflink idref="bib71" id="ref1">71</reflink>] ). This robust association is believed to be due to a number of cellular and biochemical mechanisms that occur during sleep (e.g., Peigneux et al., [<reflink idref="bib50" id="ref2">50</reflink>] ; Rasch & Born, [<reflink idref="bib53" id="ref3">53</reflink>] ), which are thought to facilitate brain plasticity and thus learning consolidation (Walker, [<reflink idref="bib72" id="ref4">72</reflink>] ). Given that the human brain is considerably more plastic during the first years of life (Huttenlocher, [<reflink idref="bib36" id="ref5">36</reflink>] ), which also constitute a time of intense learning, one might expect the links between sleep and cognition to be at least as convincing in preschool years as in adulthood. The empirical evidence is, however, still scarce. While numerous studies have found cross‐sectional relations between different indicators of sleep and cognitive or academic performance among school‐age children (see Bub, Buckhalt, & El‐Sheikh, [<reflink idref="bib12" id="ref6">12</reflink>] ; Dewald, Meijer, Oort, Kerkhof, & Bögels, [<reflink idref="bib26" id="ref7">26</reflink>] ), few investigations have studied infants or preschoolers, whose brains are undergoing major structural and functional developments, and even fewer have done so with longitudinal designs. Aiming to address these gaps, this study investigated the links between sleep at 1 year of age and cognitive performance at 4 years.</p> <hd id="AN0090064464-2">Sleep and Cognition Among Children</hd> <p>A basic notion of psychobiological development is that the functioning of lower order systems subsumes the optimal working of higher order systems (Porges, [<reflink idref="bib51" id="ref8">51</reflink>] ). It is thus proposed that sleep, as a basic biological regulatory process, serves an essential organizing function on more complex processes such as those involved in cognition (Dahl, [<reflink idref="bib22" id="ref9">22</reflink>] ; Dionne et al., [<reflink idref="bib27" id="ref10">27</reflink>] ). In line with this, there is substantial evidence that sleep of higher duration or quality is related to better cognitive performance among children (see Bub et al., [<reflink idref="bib12" id="ref11">12</reflink>] , for a review). Although most of this research has been conducted with clinical populations of children referred for sleep problems (see Owens, [<reflink idref="bib49" id="ref12">49</reflink>] ), there is also increasing evidence that sleep relates to different indicators of cognitive and academic performance among typically developing children (e.g., Bub et al., [<reflink idref="bib12" id="ref13">12</reflink>] ; Buckhalt, El‐Sheikh, & Keller, [<reflink idref="bib13" id="ref14">13</reflink>] ).</p> <p>Sadeh ([<reflink idref="bib58" id="ref15">58</reflink>] ) proposed that sleep may favor children's optimal cognitive functioning in two ways: through its role in brain maturation and memory consolidation and by promoting daytime alertness and thus favorable dispositions for learning. Given that the preschool period is a time of great neural development and remarkably rapid learning (see Kuhn, Siegler, Damon, & Lerner, [<reflink idref="bib44" id="ref16">44</reflink>] ), one may expect both these mechanisms to be especially salient during the first few years of life. A recent meta‐analysis revealed that children's age was a significant moderator of the relation between children's school performance and the three sleep parameters considered: sleep duration, sleep quality, and daytime sleepiness (Dewald et al., [<reflink idref="bib26" id="ref17">26</reflink>] ). In all indicators, relations were stronger among younger children. Although this meta‐analytic age effect pertains to school performance rather than to specific aspects of cognition, Sadeh, Gruber, and Raviv ([<reflink idref="bib61" id="ref18">61</reflink>] ) reported similar results when investigating the association between sleep and targeted cognitive tasks, wherein relations were significantly stronger among younger children. In both reports, however, the youngest children studied were 6 to 7 years old. Thus, although both these studies support the notion that relations between sleep and cognition could be especially marked among younger children, the studies did not cover the preschool period.</p> <p>There is, in fact, very little research on sleep and cognition before the school‐age period, especially in typically developing children. Scher ([<reflink idref="bib63" id="ref19">63</reflink>] ) reported that 10‐month‐olds with more fragmented sleep had lower mental development scores on a standardized measure of cognitive development (the Bayley Scales). The author cautioned, however, that longitudinal studies were needed to determine whether the observed link was merely a reflection of maturational status, or rather indicated a true role of sleep in children's cognitive development. While longitudinal designs are always invaluable in suggesting the direction of relations and ruling out a number of third‐variable explanations, they are especially critical when examining the putative impact of sleep on cognitive performance, as they serve to tease apart transient sleepiness from the persistent impact of sleep on the cognitive development process. There are, however, almost no such investigations with preschoolers, besides three studies that found that children's sleep in infancy or toddlerhood, assessed via mothers' answers to general questions included in broader measures of functioning (Dionne et al., [<reflink idref="bib27" id="ref20">27</reflink>] ; Touchette et al., [<reflink idref="bib70" id="ref21">70</reflink>] ) or with phone interviews (Dearing, McCartney, Marshall, & Warner, [<reflink idref="bib25" id="ref22">25</reflink>] ), was related to subsequent language skills.</p> <p>From a theoretical and developmental perspective, there is persistent suggestion that the level of complexity of the cognitive domain tested is critical to uncovering meaningful relations with sleep (e.g., Sadeh, [<reflink idref="bib58" id="ref23">58</reflink>] ). More complex cognitive skills, such as higher order executive functions, are expected to relate to sleep to a greater degree than indicators of general cognition, such as language and knowledge, among both adults (e.g., Horne, [<reflink idref="bib32" id="ref24">32</reflink>] ; Jones & Harrison, [<reflink idref="bib41" id="ref25">41</reflink>] ) and children (Buckhalt et al., [<reflink idref="bib13" id="ref26">13</reflink>] ; Dahl, [<reflink idref="bib22" id="ref27">22</reflink>] ). Although still somewhat speculative, these propositions have received support from experimental studies with school‐age children (Randazzo, Muehlbach, Schweitzer, & Walsh, [<reflink idref="bib52" id="ref28">52</reflink>] ; Sadeh, Gruber, & Raviv, [<reflink idref="bib62" id="ref29">62</reflink>] ). In both studies, sleep‐restricted children were outperformed by their peers on complex or executive tasks, but not on measures involving a low cognitive load.</p> <p>Such findings are believed to be attributable to the special importance of sleep for frontal brain areas subsuming higher order cognition (e.g., Cajochen, Foy, & Dijk, [<reflink idref="bib14" id="ref30">14</reflink>] ). However, children in both above experimental studies were 7 years or older, while it is in fact during the first 7 years of life that the frontal cortex undergoes a particularly intense period of development (Casey, Giedd, & Thomas, [<reflink idref="bib19" id="ref31">19</reflink>] ; Huttenlocher, [<reflink idref="bib36" id="ref32">36</reflink>] ), and may thus be particularly sensitive to influence (Singer, [<reflink idref="bib65" id="ref33">65</reflink>] ). In the only study of which we are aware that examined sleep and higher order cognition in younger children, we found that sleep at 1 year of age was related to performance on executive tasks at 18 months and 2 years of age, although it was unrelated to general cognitive ability measured by basic language skills (Bernier, Carlson, Bordeleau, & Carrier, [<reflink idref="bib6" id="ref34">6</reflink>] ). Furthermore, although general cognitive ability was positively related to executive functioning, the links between sleep and executive functioning held after adjusting for cognitive ability, indicating a specific link between sleep and executive functions. This study aimed to further examine these links by investigating the relation between sleep and cognitive performance in the same group of children, when they were 4 years of age.</p> <p>Neuroimaging studies reveal that both gray and white matter, especially in the frontal lobes, increase steadily in size between the ages of 2 and 4 years, accompanied by a significant rise in neuronal connections (Huttenlocher, [<reflink idref="bib36" id="ref35">36</reflink>] ; Huttenlocher & Dabholkar, [<reflink idref="bib37" id="ref36">37</reflink>] ). These anatomical changes are expected to translate into significant cognitive improvements, such that a fundamental qualitative shift would occur in children's capacity to integrate and manipulate complex information during the preschool years (Best & Miller, [<reflink idref="bib8" id="ref37">8</reflink>] ). Consistent with this, dramatic gains take place between 3 and 5 years, with 4‐year‐old children showing a spurt in performance on complex tasks calling upon executive skills (see De Luca & Leventer, [<reflink idref="bib24" id="ref38">24</reflink>] , for a review). The age of 4 thus appears to be an especially fruitful time to study the putative effects of early sleep patterns on complex cognition.</p> <hd id="AN0090064464-3">The Development and Measurement of Sleep in Infancy</hd> <p>The development of sleep–wake states in children (and all humans) is driven by two intrinsic bio‐regulatory processes: a homeostatic process, whereby sleep pressure accumulates with time awake and dissipates during a sleep episode, and a circadian process, which is independent of prior waking and sleep and provides cyclical clock‐like signals promoting alertness versus sleep (Jenni & LeBourgeois, [<reflink idref="bib40" id="ref39">40</reflink>] ; see also Borbély, [<reflink idref="bib9" id="ref40">9</reflink>] ). The early maturation and interaction of these two processes result in a well‐characterized development of sleep–wake states in infancy: adaptation to the day–night alternation, leading to increasingly adult‐like sleep–wake cycles. Hence, while newborns sleep roughly equal amounts of time during the day and at night, a circadian rhythm is established gradually (Halpern, MacLean, & Baumeister, [<reflink idref="bib30" id="ref41">30</reflink>] ). This process results in an overall decline in total sleep duration during the first few years of life, mostly due to a decrease in daytime sleep (Acebo et al., [<reflink idref="bib1" id="ref42">1</reflink>] ; National Sleep Foundation, [<reflink idref="bib48" id="ref43">48</reflink>] ). This should translate into an increasingly greater proportion of total sleep taking place at night. Large‐scale studies confirm that the proportion of nighttime sleep increases across infancy, from approximately 76% at 6 months to 83% at 1 year, and 87% at age 2, on average (Acebo et al., [<reflink idref="bib1" id="ref44">1</reflink>] ; Coons & Guilleminault, [<reflink idref="bib21" id="ref45">21</reflink>] ; Davis, Parker, & Montgomery, [<reflink idref="bib23" id="ref46">23</reflink>] ; Iglowstein, Jenni, Molinari, & Largo, [<reflink idref="bib38" id="ref47">38</reflink>] ).</p> <p>There is currently no consensus on the best indicators of sleep in infancy and childhood (Jenni & Carskadon, [<reflink idref="bib39" id="ref48">39</reflink>] ). It has, however, been argued that developmental considerations should guide the choice of sleep parameters likely to represent meaningful individual differences at specific ages (Bernier et al., [<reflink idref="bib6" id="ref49">6</reflink>] ; Dionne et al., [<reflink idref="bib27" id="ref50">27</reflink>] ). Based on the development of sleep–wake states presented above, the proportion of sleep taking place at night appears to constitute a developmentally appropriate index of sleep consolidation in infancy and toddlerhood, with a greater proportion reflecting a more mature organization of sleep–wake cycles. In line with this, we previously found that the proportion of nighttime sleep was the only sleep parameter assessed at 1 year that was related to subsequent executive functioning (Bernier et al., [<reflink idref="bib6" id="ref51">6</reflink>] ). In addition, Dionne et al. ([<reflink idref="bib27" id="ref52">27</reflink>] ) found that a similar ratio of nighttime to daytime sleep was more robustly related to subsequent language than either of its constituents (nighttime and daytime sleep duration) in isolation. Accordingly, we focus here on the ratio of nighttime sleep to total sleep as the core indicator of sleep consolidation. Total sleep duration, although not expected to relate to outcomes, was considered as well, given its frequent use in the literature.</p> <p>This study investigated the prospective links between sleep consolidation in infancy and 4‐year‐olds' performance on two aspects of cognition: (a) general knowledge and (b) complex executive functioning (abstract reasoning). We did so with the same children for whom we had found links between sleep and executive performance at 2 years, allowing for developmentally specific predictions above and beyond the effects already present at 2 years. It was expected that more consolidated sleep at 1 year, as indicated by a higher proportion of sleep occurring during the night, would relate to better performance on complex executive functioning at 4 years of age, although not to general knowledge. Given the marked neural and cognitive developments taking place between ages 2 and 4 described above, along with the role of sleep in brain plasticity, these longitudinal links were expected to hold above the links already identified with executive functioning at 2 years, and above cognitive development assessed concurrently with sleep at 1 year. Finally, in light of our previous findings, we expected that the links would be specific to complex executive skills, that is, that sleep would relate to children's performance on an abstract reasoning task beyond the variance in this task that would be shared with general cognitive ability (assessed through a general knowledge task).</p> <hd id="AN0090064464-4">Method</hd> <hd id="AN0090064464-5">Participants</hd> <p>The sample consisted of 58 of the original 60 mother–child dyads who took part in the first study 2 years earlier (Bernier et al., [<reflink idref="bib6" id="ref53">6</reflink>] ), in addition to 7 dyads who completed the sleep assessment at 1 year, were unable to take part in the 2‐year assessment, but returned for the 4‐year assessment. Sixty‐five families (27 boys and 38 girls) thus took part in the study reported here. Families lived in Montreal, Canada, and were recruited from birth lists randomly generated and provided to the research team by the Québec Ministry of Health and Social Services. Criteria for participation were full‐term pregnancy (i.e., at least 37 weeks of gestation) and the absence of any physical or mental disability known to the parents at the outset of the study (6 months). Sociodemographic information was gathered when infants were 6 months old. At that time, family income varied from less than $20,000 CDN to over $100,000 CDN, with an average in the $60,000 to $79,000 bracket. Mothers were between 20 and 45 years old (M = 31.8), and fathers between 23 and 44 years old (M = 34.0). Both mothers and fathers had 15.6 years of education on average (varying from 11 to 21), and most were Caucasian (89% of mothers, 76% of fathers).</p> <p>These 65 families with complete data were part of an original sample of 79 families who had sleep data at 1 year. Thus, the retention rate was 82.3%, with 14 families failing to complete follow‐up across the 3‐year interval. Attrition analyses revealed that families who left the study were not different from others on demographic or sleep variables. The only difference that approached significance was that mothers who dropped out had marginally fewer years of education (M = 14.9) than mothers who stayed in the study (M = 15.6), t(<reflink idref="bib77" id="ref54">77</reflink>) = 1.86, p = .09.</p> <hd id="AN0090064464-6">Procedure</hd> <p>This study was approved by the University of Montreal's Institutional Review Board. All participating mothers received a letter describing the study as an examination of children's sleep and development in the family context, followed by a phone call, and finally a home visit (when infants were 6 months) in which the study was described in more detail. Mothers provided written consent for participation during this visit. After each visit, the child received a present (e.g., children's book, bath toy) to thank the family for their participation.</p> <p>Mother–child dyads took part in three home visits when children were 1 (T1; M = 12.9 months, SD = 1.2), 2 (T2; M = 26.3 months, SD = 0.8), and 4 years of age (T3; M = 48.9 months, SD = 0.8). At T1, the Bayley Scales of Infant Development were administered to obtain an initial index of infants' overall cognitive functioning. Mothers completed a sleep diary for their child on 3 consecutive days in the week following the visit. At T2, the executive functioning tasks described next were administered and like the Bayley scales, they are used here as covariates when predicting child cognitive functioning at age 4. Finally, two subscales of the Wechsler Preschool and Primary Scale of Intelligence (WPPSI) were administered at T3 (age 4) to measure complex executive functioning and general cognition.</p> <hd id="AN0090064464-7">Measures</hd> <hd id="AN0090064464-8">Key Variables</hd> <hd id="AN0090064464-9">Sleep</hd> <p>The parent sleep diary is a noninvasive measure widely used in sleep research with infants and children (see Sadeh, [<reflink idref="bib60" id="ref55">60</reflink>] ). The diary records children's sleep–wake patterns over a 24‐hr period. The parent is asked to indicate, for each half hour, whether the child was awake or asleep, thus representing all periods of sleep and wake. In contrast to general sleep questionnaires, sleep diary data converge with objective sleep data gathered by actigraphy in infants and children (Acebo et al., [<reflink idref="bib1" id="ref56">1</reflink>] ; Sadeh, [<reflink idref="bib56" id="ref57">56</reflink>] , [<reflink idref="bib57" id="ref58">57</reflink>] ; Tikotzky & Sadeh, [<reflink idref="bib67" id="ref59">67</reflink>] ; Werner, Molinari, Guyer, & Jenni, [<reflink idref="bib74" id="ref60">74</reflink>] ). Although more days of assessment provide more data, parent compliance in filling out the diary becomes an increasingly greater concern with lengthier periods of diary assessment (Sadeh, [<reflink idref="bib60" id="ref61">60</reflink>] ). It has been shown that 3 days represented the optimal duration to obtain reliable data while accounting for mothers' compliance in filling out diaries of infant fussing, feeding, and sleeping patterns (St. James‐Roberts & Plewis, [<reflink idref="bib66" id="ref62">66</reflink>] ) and allowed for excellent concordance with actigraphy (Sekine et al., [<reflink idref="bib64" id="ref63">64</reflink>] ). Consequently, mothers in this study were asked to complete the diary on 3 consecutive days during which their child had a fairly usual routine. Fifty‐eight mothers (89.2%) completed the sleep diary on 3 consecutive days. In the remaining seven cases, 2 consecutive days of diary data were available, and used in analyses. Two parameters were derived from the sleep diary: total daily sleep duration, and ratio of nighttime sleep (between 7 p.m. and 8 a.m.) to total sleep. Two infants went to bed earlier than 7 p.m. on at least 1 day of assessment, and four others got up later than 8 a.m. The thresholds were adjusted in those cases, to reflect infants' actual night sleep.</p> <p>To increase reliability of estimates and in light of the average between‐day correlations for total sleep duration (r = .61, p < .001) and ratio of nighttime sleep (r = .64, p < .001), values for the two sleep parameters were averaged across the 3 (or 2) days of assessment. Average sleep duration and sleep ratio were negatively related, r = −.25, p < .05.</p> <hd id="AN0090064464-10">Cognitive performance at age 4</hd> <p>Children's cognitive performance was assessed at age 4 with two subscales of the Wechsler Preschool and Primary Scale of Intelligence (WPPSI–III; Wechsler, [<reflink idref="bib73" id="ref64">73</reflink>] ). Designed for children aged 2.5–7.25 years, the WPPSI is a well‐validated and standardized test of intellectual functioning that provides subtest and composite scores in verbal and nonverbal cognitive domains. The WPPSI–III is the second revised version of the original test and is composed of 14 subtests (7 verbal, 5 performance, and 2 processing speed). The Information subscale is a core verbal subtest that assesses children's ability to acquire, retain, and retrieve general factual knowledge (scaled score; M = 10, SD = 3). It is composed of 34 items (6 pictures, 28 verbal). This subtest was chosen to index child general cognitive ability as it taps into children's capacity to retrieve and use information from their everyday lives, their crystallized intelligence, and their long‐term memory (Wechsler, [<reflink idref="bib73" id="ref65">73</reflink>] ). The Matrix Reasoning subscale is a core performance subtest for children aged 4–7.25 years. It was used as a measure of complex executive functioning (scaled score; M = 10, SD = 3). This subtest, composed of 29 items, requires children to complete partially filled grids of complex visual patterns and analogies by selecting the picture that best continues the sequence from a set of four to five possible answers. Four types of matrices are shown to children, namely, continuous and discrete pattern completion, analogical reasoning, serial reasoning, and classification (Wechsler, [<reflink idref="bib73" id="ref66">73</reflink>] ). This subtest taps into complex executive functions such as abstract reasoning skills, concept formation, and problem‐solving skills.</p> <hd id="AN0090064464-11">Control Variables</hd> <hd id="AN0090064464-12">Cognitive functioning at 1 year</hd> <p>Children's general cognitive functioning concurrent with the sleep assessment was rated with the Mental Development Index of the Bayley Scales of Infant Development (Bayley, [<reflink idref="bib5" id="ref67">5</reflink>] ), a standardized test of cognitive development for children aged 1–42 months.</p> <hd id="AN0090064464-13">Executive functioning at 2 years</hd> <p>At 2 years, a battery of executive tasks was used, consisting of the following tasks (see Bernier et al., [<reflink idref="bib6" id="ref68">6</reflink>] , for a detailed description): Spin the Pots (Hughes & Ensor, [<reflink idref="bib34" id="ref69">34</reflink>] ), Delay of Gratification (Kochanska, Murray, & Harlan, [<reflink idref="bib42" id="ref70">42</reflink>] ), Shape Stroop (Kochanska et al., [<reflink idref="bib42" id="ref71">42</reflink>] ), and Baby Stroop (adapted from Hughes & Ensor, [<reflink idref="bib34" id="ref72">34</reflink>] ). We previously found (Bernier et al., [<reflink idref="bib6" id="ref73">6</reflink>] ) that these tasks loaded on two factors, Impulse Control and Conflict‐Executive functioning (EF). While Impulse Control is the ability to delay or suppress an impulsive response, Conflict‐EF represents the ability to respond appropriately in the face of a salient conflicting response option. On “conflict” tasks, the child is not only to suppress a dominant response as in an impulse control task, but also to provide a novel response that is incompatible with the prepotent one (Carlson, [<reflink idref="bib16" id="ref74">16</reflink>] ). Scores for Spin the Pots, Shape Stroop, and Baby Stroop loaded on the first factor (Conflict‐EF, mostly requiring working memory and set shifting), while only the Delay of Gratification trials loaded on the second factor (Impulse Control). Two standardized averaged scores were therefore computed and were reported to relate positively to the 1‐year nighttime sleep ratio (Bernier et al., [<reflink idref="bib6" id="ref75">6</reflink>] ). Accordingly, they will be used here as covariates in the main regression analyses when predicting 4‐year cognitive performance from 1‐year sleep (imputing group means to the seven families with missing 2‐year data).</p> <hd id="AN0090064464-14">Results</hd> <hd id="AN0090064464-15">Preliminary Analyses</hd> <p>Infants slept between 9 and 16.5 hr per day at 1 year (M = 13.1, SD = 1.4), and 63% to 91.5% of this sleep time occurred during the night (M = 78.7, SD = 5.8). At 4 years, their scaled scores on the Information subscale of the WPPSI ranged from 4 to 17 (M = 11.0, SD = 2.4), while scaled scores on Matrix Reasoning ranged from 1 to 17 (M = 12.2, SD = 2.6). The correlation between the Information and Matrix Reasoning subscale scores was r = .22, p < .05.</p> <p>We next examined the zero‐order correlations between all potential covariates (child sex and birth weight, maternal and paternal age and education, family income, 1‐year cognitive functioning, and 2‐year EF scores) and the outcomes, namely, age 4 scores on Information and Matrix Reasoning. First, in light of their intercorrelations (between.58 and.68), maternal and paternal education and family income were standardized and averaged into a global family socioeconomic status (SES) index. Family SES and 1‐year cognitive functioning were related to children's scores for both Information (r = .40, p < .001 and r = .34, p < .01, respectively) and Matrix Reasoning (r = .23, p < .05 and r = .27, p < .05, respectively). They were therefore covaried in final regression models. Child sex (both ts < 1.21, ns) and birth weight as well as parents' age (all rs < .16, ns) were unrelated to either WPPSI subtest and therefore not considered further. Finally, the Conflict and Impulse Control EF scores were unrelated to children's subsequent scores on the WPPSI (all rs < .18, ns). Nonetheless, in light of our previous findings indicating a relation between sleep and these EF scores, and with the aim of performing conservative tests in this study, the two EF scores were averaged (r = .30, p < .05) and covaried in final regression models.</p> <hd id="AN0090064464-16">Main Analyses</hd> <p>Table [NaN] presents the zero‐order correlations between the two sleep parameters (sleep duration and sleep ratio) and the four cognitive functioning scores (1‐year cognitive functioning, 2‐year executive functioning, Information, Matrix Reasoning). As previously reported (Bernier et al., [<reflink idref="bib6" id="ref76">6</reflink>] ), total sleep duration at 1 year was unrelated to cognition at 1 and 2 years of age, whereas the 1‐year sleep ratio was unrelated to cognitive functioning at 1 year, but significantly related to child executive functioning at 2 years. In this study, sleep duration was, as expected, unrelated to children's cognitive performance on either the Information subscale (r = −.01, ns) or the Matrix Reasoning subscale (r = −.03, ns) at 4 years of age. In contrast, the ratio of nighttime sleep was related to children's scores on Matrix Reasoning (r = .31, p < .01), but not on Information (r = .09, ns). These initial results are consistent with the hypothesized specific relations between sleep consolidation and higher order cognition. Note that to ensure that the results were specific to the ratio of nighttime sleep, exploratory analyses were conducted using two other indices of sleep consolidation that can be derived from the sleep diary: nighttime sleep duration and longest uninterrupted sleep bout. These two parameters were unrelated to children's matrix reasoning performance, r = −. 03, ns, and r = .02, ns, and general cognition, r = −. 01, ns, and r = −.08, ns.</p> <p>Zero‐Order Correlations Between the Two Sleep Parameters at 1 Year and Cognitive Functioning at 1, 2, and 4 Years of Age</p> <p> <ephtml> <table><tr><th align="left" /><th align="center">1‐year sleep duration</th><th align="center">1‐year nighttime sleep ratio</th></tr><tr><td align="left">1‐year cognitive functioning</td><td align="char" char=".">.11</td><td align="char" char=".">.15</td></tr><tr><td align="left">2‐year executive functioning</td><td align="char" char=".">−.09</td><td align="char" char=".">.30</td></tr><tr><td align="left">4‐year WPPSI scores</td></tr><tr><td align="left">Information</td><td align="char" char=".">−.01</td><td align="char" char=".">.09</td></tr><tr><td align="left">Matrix Reasoning</td><td align="char" char=".">−.03</td><td align="char" char=".">.31</td></tr></table> </ephtml> </p> <p>1 Note. WPPSI = Wechsler Preschool and Primary Scale of Intelligence.</p> <p>2 *p < .05. **p < .01.</p> <p>A hierarchical regression model was estimated next, with children's scores on Matrix Reasoning as the dependent variable. As the most distal potential predictor, family SES was entered first, followed by the two indicators of children's prior cognitive functioning in a second block (1‐year Bayley scores and 2‐year EF composite score), and by the sleep ratio in a third block. The overall model was significant, F(<reflink idref="bib4" id="ref77">4</reflink>, 65) = 3.91, p < .05, explaining 15.9% of the variance in children's scores on Matrix Reasoning. As displayed in Table [NaN] (upper panel), family SES accounted for a significant 5.3% of variance, while the indicators of prior cognitive functioning jointly contributed a marginal additional 4.1% to the prediction. Finally, the sleep ratio contributed a significant unique 6.5% of explained variance above these covariates.</p> <p>Summary of Regression Analyses Predicting Child Performance on Matrix Reasoning in the WPPSI</p> <p> <ephtml> <table><tr><th align="left">Model and steps</th><th align="center">R²</th><th align="center">∆R²</th><th align="center">F change</th><th align="center">β</th></tr><tr><td align="left">1. Family SES</td><td align="char" char=".">.053</td><td align="left" /><td align="char" char=".">3.51</td><td align="char" char=".">.23</td></tr><tr><td align="left">2. 1‐year cognitive functioning</td><td align="left" /><td align="left" /><td align="left" /><td align="char" char=".">.21</td></tr><tr><td align="left">2‐year executive functioning</td><td align="char" char=".">.094</td><td align="char" char=".">.041</td><td align="char" char=".">3.16</td><td align="char" char=".">.09</td></tr><tr><td align="left">3. 1‐year % night sleep</td><td align="char" char=".">.159</td><td align="char" char=".">.065</td><td align="char" char=".">4.80</td><td align="char" char=".">.26</td></tr><tr><td align="left">1. Family SES</td><td align="char" char=".">.053</td><td align="left" /><td align="char" char=".">3.51</td><td align="char" char=".">.23</td></tr><tr><td align="left">2. 1‐year cognitive functioning</td><td align="left" /><td align="left" /><td align="left" /><td align="char" char=".">.21</td></tr><tr><td align="left">2‐year executive functioning</td><td align="char" char=".">.094</td><td align="char" char=".">.041</td><td align="char" char=".">3.16</td><td align="char" char=".">.09</td></tr><tr><td align="left">3. Information subscale</td><td align="char" char=".">.101</td><td align="char" char=".">.007</td><td align="char" char=".">0.44</td><td align="char" char=".">.09</td></tr><tr><td align="left">4. 1‐year % night sleep</td><td align="char" char=".">.165</td><td align="char" char=".">.064</td><td align="char" char=".">4.69</td><td align="char" char=".">.26</td></tr></table> </ephtml> </p> <ulist> <item>3 Note. WPPSI = Wechsler Preschool and Primary Scale of Intelligence; SES = socioeconomic status.</item> <item>4 †p < .10. *p < .05.</item> </ulist> <p>To perform an especially stringent test focusing on the variance in children's Matrix Reasoning scores not explained by concurrent general cognitive ability, we ran a second regression model similar to the first one, except that scores on the Information subscale were entered in the third block, followed by sleep in a last, fourth block. As displayed in Table [NaN] (lower panel), although scores on the Information subscale were no longer significantly related to Matrix Reasoning after accounting for family SES and children's prior cognitive functioning (β = .09, ns), the set of covariates jointly explained 10.1% of the variance in child performance on Matrix Reasoning. After accounting for these, the contribution of sleep was almost unchanged, explaining a significant 6.4% of unique variance over and above all covariates.</p> <hd id="AN0090064464-17">Exploratory Analyses</hd> <p>To ensure that the nonsignificant zero‐order correlations presented above did not mask meaningful results blurred by suppressor effects, we ran three additional regression equations with total sleep duration (rather than the ratio) as the predictor, and/or child score on the Information subscale as the outcome. These analyses confirmed the absence of significant relations, whether concerning total sleep duration or scores on Information. Hence, after accounting for the same set of covariates as above, total sleep duration was unrelated to scores on Information (β = .08, ns) and Matrix Reasoning (β = .05, ns), and the sleep ratio was unrelated to child performance on the Information subscale (β = .02, ns). Thus, the longitudinal links between sleep and cognition were specific to the sleep ratio and to complex cognition.</p> <hd id="AN0090064464-18">Discussion</hd> <p>The aim of this study was to examine the links between sleep consolidation in infancy and cognitive performance at preschool age. It was expected that more consolidated sleep would relate to complex executive functioning although not to general cognitive ability. Given the presumed role of sleep in frontal brain development, these links were expected to hold above children's cognitive performance in prior years. Overall, the results supported these hypotheses. Hence, children getting higher proportions of their sleep at night as infants were found to perform better on a task calling upon complex executive functions such as abstract reasoning, concept formation, and problem‐solving skills 3 years later, but did not show better general cognition (factual knowledge). Total 1‐year sleep duration was not related to either aspect of 4‐year cognition. Finally, the sleep ratio was uniquely related to executive functioning, above and beyond the variance shared by executive functioning with general cognition, both prior and current. All relations held after controlling for family SES and prior executive functioning.</p> <p>These results significantly extend those that we reported when the same children were 2 years younger: We had then found that a higher ratio of nighttime sleep at age 1, but not total sleep duration, was related to higher subsequent executive functioning although not to general cognition (Bernier et al., [<reflink idref="bib6" id="ref78">6</reflink>] ). We had further found that the links with the sleep ratio were specific to higher order cognition, as they held above the variance shared by executive functioning with general cognition. Importantly, the current results showing the same pattern are statistically independent from these prior ones, given that we controlled for 2‐year executive functioning in the analyses. Overall then, the current findings were functionally and developmentally specific, in that they held above both current and prior general cognition, and above prior executive functioning.</p> <p>There thus appears to be increasing evidence that the hypothesized localized function of sleep for frontal brain areas subsuming complex cognition, which is suggested by both behavioral (see Horne, [<reflink idref="bib32" id="ref79">32</reflink>] ; Jones & Harrison, [<reflink idref="bib41" id="ref80">41</reflink>] ) and electrophysiological (Cajochen, Knoblauch, Krauchi, Renz, & Wirz‐Justice, [<reflink idref="bib15" id="ref81">15</reflink>] ; Cajochen et al., [<reflink idref="bib14" id="ref82">14</reflink>] ; Werth, Achermann, & Borbély, [<reflink idref="bib75" id="ref83">75</reflink>] ) evidence among adults, may appear very early in life. The results of the current longitudinal study, focusing on EF at ages 2 (Bernier et al., [<reflink idref="bib6" id="ref84">6</reflink>] ) or 4 (this article), are in keeping with findings of experimental studies with school‐age children (Randazzo et al., [<reflink idref="bib52" id="ref85">52</reflink>] ; Sadeh et al., [<reflink idref="bib62" id="ref86">62</reflink>] ), all pointing to specific links between sleep and complex cognition. They are, however, the only findings of which we are aware that are based on an assessment of sleep during infancy, a period witnessing some of the most pronounced developments in child sleep (Acebo et al., [<reflink idref="bib1" id="ref87">1</reflink>] ; National Sleep Foundation, [<reflink idref="bib48" id="ref88">48</reflink>] ), and investigating children's cognitive performance up to 3 years later. The consistency of results across longitudinal and experimental designs, and among different age groups and samples, provides strong suggestion that sleep may favor the development of higher order cognitive functions requiring prefrontal cortex involvement, at different developmental periods starting in infancy.</p> <p>The longitudinal design used here, along with the controls for prior cognition that were implemented, also suggests that a true developmental process is likely to be at play, not only due to transient sleepiness influencing children's immediate performance on more complex tasks. One may thus hypothesize that infant sleep could impact developing brain structures in the first years of life, thereby setting in motion a cascade of neural effects carrying substantial implications for later executive functioning, at least into the preschool years. Although the exact mechanisms through which sleep would impact infant brain development have yet to be investigated, adult studies that have demonstrated that sleep plays a crucial role in learning and memory (see Rauchs, Desgranges, Foret, & Eustache, [<reflink idref="bib54" id="ref89">54</reflink>] ; Walker, [<reflink idref="bib71" id="ref90">71</reflink>] , [<reflink idref="bib72" id="ref91">72</reflink>] ) are useful in this regard. Animal and human studies have shown that the neuronal circuits active during previous learning are reactivated during sleep (Peigneux et al., [<reflink idref="bib50" id="ref92">50</reflink>] ; Rasch & Born, [<reflink idref="bib53" id="ref93">53</reflink>] ). In addition, proteins associated with brain plasticity and learning are up‐regulated during sleep (Basheer, Brown, Ramesh, Begum, & McCarley, [<reflink idref="bib4" id="ref94">4</reflink>] ; Cirelli, [<reflink idref="bib20" id="ref95">20</reflink>] ). It is also proposed that sleep would induce a progressive downscaling of synaptic strength accumulated during the day to reach an energetically suitable level and make efficient use of cerebral gray matter (Tononi & Cirelli, [<reflink idref="bib69" id="ref96">69</reflink>] ), and that brain glycogen, a source of stored energy that is used to support brain activity, is depleted during activities that tax executive control systems and restored during sleep (Gaillot, [<reflink idref="bib28" id="ref97">28</reflink>] ). All these observed or proposed mechanisms could also be at play during infancy and early childhood and in fact, they may play an especially potent role during these early periods that witness sharp developments in brain connectivity, particularly in the frontal areas subsuming complex cognition (Casey et al., [<reflink idref="bib19" id="ref98">19</reflink>] ; Huttenlocher, [<reflink idref="bib36" id="ref99">36</reflink>] ).</p> <p>Another contribution of this study pertains to the assessment of sleep. A striking aspect of the sleep research involving infants and children is how different sleep parameters are associated with positive outcomes in different studies, and how the same sleep parameters show different (e.g., Anders, Keener, & Kraemer, [<reflink idref="bib2" id="ref100">2</reflink>] ; Gertner et al., [<reflink idref="bib29" id="ref101">29</reflink>] ) and sometimes opposite relations (e.g., Borghese, Minard, & Thoman, [<reflink idref="bib11" id="ref102">11</reflink>] ) to the same outcomes at different ages. We and others have argued that these age differences are a key aspect of the inconsistency in findings, and therefore that developmental considerations should guide the choice of sleep parameters likely to represent meaningful individual differences at specific ages (Bernier et al., [<reflink idref="bib6" id="ref103">6</reflink>] ; Dionne et al., [<reflink idref="bib27" id="ref104">27</reflink>] ). The choice of the nighttime sleep ratio in this study was based on the fact that a primary regulation task during the first years of life is to consolidate sleep into the night period, which mostly manifests itself through a decrease in daytime sleep (Iglowstein et al., [<reflink idref="bib38" id="ref105">38</reflink>] ). A greater proportion of nighttime sleep can thus be considered a marker of a more mature organization of sleep–wake states in very young children. The fact that this ratio had previously been found to be the only sleep indicator that related to child 2‐year executive functioning, and was found here to predict 4‐year executive functioning over and above prior levels, along with Dionne et al.'s ([<reflink idref="bib27" id="ref106">27</reflink>] ) similar findings, suggest that the proportion of total sleep taking place at night may tap into especially meaningful variation in sleep regulation at 1 year of age.</p> <p>In fact, the specificity of the results to this ratio, along with the near‐zero relations we found between executive functioning and total or nighttime sleep duration, and with the well‐documented decline in sleep duration throughout the first years of life, converge to suggest that the putative cognitive benefits of sleep in infancy and early childhood are most likely not due to the quantity of sleep, but rather to its maturity, quality, or organization. For instance, slow‐wave activity (SWA; spectral power between 0.5 and 4.0 Hz during nonrapid‐eye‐movement [nREM] sleep) has been proposed to contribute to cortical maturation (Ringli & Huber, [<reflink idref="bib55" id="ref107">55</reflink>] ). This suggestion is based notably on the observation of a parallel time course of synaptic density, brain metabolism, and SWA during development (e.g., Huttenlocher & Dabholkar, [<reflink idref="bib37" id="ref108">37</reflink>] ), by the numerous studies suggesting a causal role of SWA in learning and consolidation among adults (e.g., Huber, Ghilardi, Massimini, & Tononi, [<reflink idref="bib33" id="ref109">33</reflink>] ; Landsness et al., [<reflink idref="bib46" id="ref110">46</reflink>] ; Marshall, Helgadóttir, Mölle, & Born, [<reflink idref="bib47" id="ref111">47</reflink>] ) and by the recent observation that during children's and adolescents' sleep, there is more SWA in the specific cortical regions undergoing anatomical maturation (Kurth et al., [<reflink idref="bib45" id="ref112">45</reflink>] ). Ringli and Huber ([<reflink idref="bib55" id="ref113">55</reflink>] ) thus propose that SWA may play an active role in the regulation of cortical synaptic strength. This, in turn, is likely to play a significant role in infants' and children's brain maturation and executive development.</p> <p>Consequently, one may speculate that more mature sleep in infancy and early childhood could promote learning and brain development because its organization is perhaps better suited to fulfill this critical function. For example, it might be constituted of proportionally more SWA than less mature sleep, and thus be more conducive to brain plasticity underlying learning and consolidation. However, given that the mechanisms accounting for the beneficial effects of sleep on child cognition have yet to be identified, it may also be that more mature sleep shows other, as yet unidentified characteristics that would be conducive to brain development and learning (e.g., proportions of REM vs. nREM sleep, more restful sleep leading to daytime alertness, more efficient up‐regulation of proteins, better downscaling of synaptic strength, etc.). Such processes need not follow a dose–response pattern with sleep duration, as suggested for instance by the observation that a 90‐min nap allows for similar learning consolidation of certain skills as a full night sleep (Korman et al., [<reflink idref="bib43" id="ref114">43</reflink>] ). Overall, we would argue that the time is ripe for developmental researchers and sleep scientists to join forces so as to investigate these questions that are likely to push the field forward.</p> <p>It is also the case, however, that the results of this study could reflect maturation of the central nervous system at two different ages, in the absence of a causal link between sleep and executive functioning. Hence, neural maturation could be reflected both in the early organization of sleep–wake states and in later executive functioning, rather than being the mechanism accounting for a causal link between the two. Another potential common cause to sleep and executive functioning involves the family context. Indeed, while the development of sleep–wake states is thought to be driven largely by maturational and constitutional factors (e.g., Jenni & LeBourgeois, [<reflink idref="bib40" id="ref115">40</reflink>] ), there is also increasing evidence that young children's sleep is related to social factors, such as the quality of parent–infant interactions (Bordeleau, Bernier, & Carrier, [<reflink idref="bib10" id="ref116">10</reflink>] ; Tikotzky, Sadeh, & Glickman‐Gavrieli, [<reflink idref="bib68" id="ref117">68</reflink>] ). Importantly, we and others have reported that these social factors are also implicated in children's executive development (e.g., Bernier, Carlson, Deschênes, & Matte‐Gagné, [<reflink idref="bib7" id="ref118">7</reflink>] ; Hammond, Müller, Carpendale, Bibok, & Liebermann‐Finestone, [<reflink idref="bib31" id="ref119">31</reflink>] ). Hence, the links found here between child sleep and executive functioning might be due to a common underlying influence of stable and harmonious parent–child interactions, which could serve a regulatory function on both sleep consolidation and executive functioning in young children.</p> <p>Developmental sleep research will benefit from increased reliance on objective sleep measures such as actigraphy, polysomnography, or videosomnography. In contrast to general sleep questionnaires, sleep diary data converge with objective sleep data gathered by actigraphy, including with infants and children (Acebo et al., [<reflink idref="bib1" id="ref120">1</reflink>] ; Sadeh, [<reflink idref="bib56" id="ref121">56</reflink>] , [<reflink idref="bib57" id="ref122">57</reflink>] ; Werner et al., [<reflink idref="bib74" id="ref123">74</reflink>] ), and are proposed to be interchangeable with actigraphy when assessing certain sleep parameters (Sadeh, [<reflink idref="bib59" id="ref124">59</reflink>] ; Werner et al., [<reflink idref="bib74" id="ref125">74</reflink>] ). However, a sleep diary yields less individual variation than actigraphy (Sadeh, [<reflink idref="bib56" id="ref126">56</reflink>] , [<reflink idref="bib59" id="ref127">59</reflink>] ; Werner et al., [<reflink idref="bib74" id="ref128">74</reflink>] ), and it is thus increasingly recommended that developmental studies use objective methods to assess child sleep (Sadeh, [<reflink idref="bib60" id="ref129">60</reflink>] ). Other limitations of this study include the relatively small sample size, and the failure to assess child sleep concurrently to the 4‐year cognitive assessment. A cross‐lagged design, entailing assessments of child sleep and cognitive performance at both time points, would have allowed for firmer demonstration of the direction of relations. As mentioned in the Introduction, however, longitudinal studies of child sleep and cognition are very rare, and almost nonexistent when examining preschoolers or aspects of higher order cognition such as executive functioning. The current results suggest that the continued use of longitudinal designs to investigate these questions is likely to prove fruitful for developmental sleep research. Finally, the lack of significant relations we found between 2‐ and 4‐year executive functioning might seem counterintuitive. Recall, however, that different executive functions were tapped at the two ages. While the 2‐year tasks assessed working memory, set shifting, and inhibition, the 4‐year task rather tapped into problem solving and abstract reasoning, which are conceptualized as complex executive functions, not yet developed in toddlerhood (Anderson, [<reflink idref="bib3" id="ref130">3</reflink>] ). In fact, young children's performance on different facets of executive function has been observed to be weakly or uncorrelated in other longitudinal studies, although rank order of EF abilities within cohort are stable (Carlson, Mandell, & Williams, [<reflink idref="bib17" id="ref131">17</reflink>] ; Carlson, Rochette, Kreher, Harms, & Desjardins, [<reflink idref="bib18" id="ref132">18</reflink>] ; Hughes & Ensor, [<reflink idref="bib35" id="ref133">35</reflink>] ). Therefore, while early‐developing executive functions are likely to lay the groundwork for the development of more advanced executive processes, the exact magnitude of stability estimates may vary substantially across ages and specific functions.</p> <p>This study is the first to use a longitudinal design starting in infancy to investigate the relations between child sleep and higher order cognition. The results suggested that greater proportions of total sleep occurring at nighttime, but not total sleep duration, were related to children's higher EF performance 3 years later, controlling for initial cognitive levels. While research should investigate these links further with objective sleep assessments, experimental designs and at other developmental periods, the findings provide further suggestion for the critical role of sleep in children's healthy development.</p> <ref id="AN0090064464-19"> <title>Footnotes</title> <blist> <bibl id="bib1" idref="ref42" type="bt">1</bibl> <bibtext>Annie Bernier, Miriam H. Beauchamp, Andrée‐Anne Bouvette‐Turcot, and Julie Carrier, Department of Psychology, University of Montreal; Stephanie M. Carlson, Institute of Child Development, University of Minnesota. </bibtext> </blist> <blist> <bibl id="bib2" idref="ref100" type="bt">2</bibl> <bibtext>The research described in this article was supported by grants from the Social Sciences and Humanities Research Council of Canada, the Fonds de Recherche en Santé du Québec, and the Fonds Québécois de Recherche sur la Société et la Culture to the first author. We gratefully acknowledge Natasha Whipple, Émilie Rochette, Natasha Ballen, Isabelle Demers, Jessica Laranjo, Stéphanie Bordeleau, Célia Matte‐Gagné, Marie‐Ève Bélanger, Véronique Jarry‐Boileau, Marie Deschênes, Chantal Mongeau, Marie‐Pier Nadeau‐Noël, and Nadine Marzougui for help with data collection. 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  Data: Sleep and Cognition in Preschool Years: Specific Links to Executive Functioning
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  Data: <searchLink fieldCode="AR" term="%22Bernier%2C+Annie%22">Bernier, Annie</searchLink><br /><searchLink fieldCode="AR" term="%22Beauchamp%2C+Miriam+H%2E%22">Beauchamp, Miriam H.</searchLink><br /><searchLink fieldCode="AR" term="%22Bouvette-Turcot%2C+Andrée-Anne%22">Bouvette-Turcot, Andrée-Anne</searchLink><br /><searchLink fieldCode="AR" term="%22Carlson%2C+Stephanie+M%2E%22">Carlson, Stephanie M.</searchLink><br /><searchLink fieldCode="AR" term="%22Carrier%2C+Julie%22">Carrier, Julie</searchLink>
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  Data: <searchLink fieldCode="SO" term="%22Child+Development%22"><i>Child Development</i></searchLink>. Sep-Oct 2013 84(5):1542-1553.
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  Data: Wiley-Blackwell. 350 Main Street, Malden, MA 02148. Tel: 800-835-6770; Tel: 781-388-8598; Fax: 781-388-8232; e-mail: cs-journals@wiley.com; Web site: http://www.wiley.com/WileyCDA/
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  Data: 12
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  Data: <searchLink fieldCode="DE" term="%22Sleep%22">Sleep</searchLink><br /><searchLink fieldCode="DE" term="%22Executive+Function%22">Executive Function</searchLink><br /><searchLink fieldCode="DE" term="%22Infants%22">Infants</searchLink><br /><searchLink fieldCode="DE" term="%22Preschool+Children%22">Preschool Children</searchLink><br /><searchLink fieldCode="DE" term="%22Cognitive+Ability%22">Cognitive Ability</searchLink><br /><searchLink fieldCode="DE" term="%22Mothers%22">Mothers</searchLink>
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  Data: 10.1111/cdev.12063
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  Data: This study investigated the prospective links between sleep in infancy and preschoolers' cognitive performance. Mothers of 65 infants completed a sleep diary when infants were aged 1 year, and children completed two subscales of the Wechsler Preschool and Primary Scale of Intelligence at 4 years, indexing general cognitive ability and complex executive functioning. Consistent with hypotheses, children getting higher proportions of their sleep at night as infants were found to perform better on executive functions, but did not show better general cognition. Relations held after controlling for family socioeconomic status and prior cognitive functioning. These findings suggest that the special importance of sleep for higher order cognition, documented among adults, may appear very early in life.
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  Data: 2014
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        Value: 10.1111/cdev.12063
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      – SubjectFull: Sleep
        Type: general
      – SubjectFull: Executive Function
        Type: general
      – SubjectFull: Infants
        Type: general
      – SubjectFull: Preschool Children
        Type: general
      – SubjectFull: Cognitive Ability
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      – SubjectFull: Mothers
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      – SubjectFull: Wechsler Preschool and Primary Scale of Intelligence
        Type: general
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      – TitleFull: Sleep and Cognition in Preschool Years: Specific Links to Executive Functioning
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            NameFull: Bernier, Annie
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            NameFull: Beauchamp, Miriam H.
      – PersonEntity:
          Name:
            NameFull: Bouvette-Turcot, Andrée-Anne
      – PersonEntity:
          Name:
            NameFull: Carlson, Stephanie M.
      – PersonEntity:
          Name:
            NameFull: Carrier, Julie
    IsPartOfRelationships:
      – BibEntity:
          Dates:
            – D: 01
              M: 01
              Type: published
              Y: 2013
          Identifiers:
            – Type: issn-print
              Value: 0009-3920
          Numbering:
            – Type: volume
              Value: 84
            – Type: issue
              Value: 5
          Titles:
            – TitleFull: Child Development
              Type: main
ResultId 1