| Sleep patterns refer to the behaviors that formed the natural human sleep/wake cycles and are formed in infancy and can be sustained into adulthood.Middlechildhood is an especially important period for sleep developmental,given the rapid cognitive,physical,and social-emotional changes when children entering school system.However,previous studies have less nuanced the developmental changes in different sleep characteristics of children;furthermore,most of the existing findings are based on variable-centered approaches with limited effectiveness in capturing the complexity and heterogeneous nature of children sleep.Migrant children may be more likely to encounter sleep problems and to experience more negative outcomes as a result of poor sleep,but have been underrepresented in previous studies of sleep.The present thesis used a three-year longitudinal design with a sample of migrant children(306 girls and 395 boys)living in urban Shanghai.We adopted variablecentered and person-centered approaches and explored the developmental changes in children’s sleep patterns,the impacts of social-contextual factors on their sleep development,and the relationship between sleep patterns and adjustments.In the first part of this thesis,I first examined linear trends of sleep patterns from children’s 2nd to 5th grade based on a variable-centered perspective.Our findings suggested that children tended to have shorter sleep duration,later sleep midpoint,and greater social jetlag as they aged.However,school-aged girls had greater weekend catch-up sleep and earlier school day sleep midpoint than boys,and girls showed a significant increase in weekend catch-up sleep over time,while it remained stable for boys.Next,I adopted a person-centered approach to identify sleep profiles and transition scenarios across time.Four distinct sleep profiles were identified at both 3 time points: Short-sleeping owls,Larks,Normative sleepers,and Irregular sleepers.In general,the Normative sleepers showed the greatest stability across time,followed by Short-sleeping owls,while the other two profiles showed the relatively variable transitions.Girls are more prone to be Irregular sleepers in Grade2 than boys.And boys showed greater variability in sleep transition scenarios the middle childhood than girls.In the second part of this thesis,I first examined the impacts of family and school factors on changes in sleep patterns through a variable-centered perspective.Results indicated that children with parental monitoring on sleep reported longer sleep duration,shorter weekend catch-up sleep,and less social jetlag,and fewer increases in social jetlag over time compared to those lack of monitoring;less harsh parenting and greater perceived teacher and peer relationships were associated with fewer changes in sleep regularity.Next,I further investigated the effects of social-contextual factors on sleep profiles and transition scenarios based on the person-centered findings.Results showed that children from families with higher SES,with parental monitoring of sleep were more likely to be classified into Larks or Normative sleepers,while those who experienced a higher level of harsh parenting and perceived more negative social relationships in school were more likely to be classified into Short-sleeping owls or Irregular sleepers.In addition,children in Normative sleepers profile relatively sustained this profile from Grade 2 to Grade 5,their transitions were not influenced by any other family or school factors other than parental monitoring.In contrast,the Larks,Short-sleeping owls and Irregular sleepers are more susceptible to social environmental factors at each time point of transition.In the third part of this thesis,I first examined the prospective bi-directional relationships between multiple sleep variables and a variety of indicators of child adjustment through a variable-centered perspective.Results suggested that sleep duration/timing variables in Grade 2 mostly predicted emotional and behavioral problems in Grade 3,while emotional and behavioral problems in Grade 3 mostly predicted sleep irregularity variables in Grade 5.Additionally,the reciprocal associations between sleep and behaviors were evidenced stronger in boys than girls.Next,from a person-centered perspective,I examined the associations between sleep profiles/ transition scenarios and outcomes and to identify potential risk sleep profiles/transition scenarios.Results indicated that Normative sleepers was the optimal profiles in our sample and Larks was a sub-optimal profile.While Short-sleeping owls and Irregular sleepers functioned as unfavorable sleep subtypes,as they are associated with more negative outcomes.Furthermore,as expected,negative transitions(i.e.,from a favorable profile to an unfavorable profile)have detrimental effects on children’s emotional and behavioral adjustment and academic performance.The present thesis integrated variable-centered and person-centered approaches and provide a more nuanced insight into children’s sleep development.Findings of the current study help shed light on identifying unfavorable sleep profiles in child development among migrant children and considering risk and protective factors for sleep development.We hope to inform practitioners to develop tailored prevention or intervention programs for children sleep problems. |
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