The i Heart Rhythm Project: Healthy Sleep and Behavioral Rhythms for Obesity Prevention

Body Mass Index (BMI) is the most common indicator of body size and has been consistently correlated with metabolic problems in children. Participants' height and weight will be measured using established protocols. BMI (kg/m2) will be computed and BMI %ile and BMIz will be calculated from age and gender normative data. BMI %ile will determine weight status group. Change in BMI and BMIz are the best proxy measures for change in fat mass and standardized fat mass and will assess exploratory hypotheses. Change in BMI will serve as the primary outcome for the fully powered randomized controlled trial. For the current application, feasibility criteria will serve as the primary outcome.

Circadian phase can be examined by measuring the circadian timing of melatonin onset under dim light conditions (dim light melatonin onset; DLMO). Compared to markers of endogenous circadian rhythms, melatonin is relatively robust. Salivary DLMO measures have demonstrated high intraclass correlations (.93) with plasma and sensitivity and specificity comparable to plasma assays. Following established procedures with children, salivary DLMO will be collected on a weekday evening in the laboratory under dim light conditions (<40 lux), via a cheek swab every hour beginning 5 hours prior to and ending 1 hour following typical bedtime. Saliva samples will be centrifuged, frozen, and assayed using radioimmunoassay test kits. DLMO phase will be determined using linear interpolation across the time points before and after melatonin concentration increased to and remained above 4pg/mL.

Actigraphs (GT3X-BT, Pensacola, FL) worn on the wrist of the dominant hand 24 hours a day for 7 days will measure sleep duration and timing of sleep onset and waking. Wrist placement reliably measures sleep duration in adolescents. Sleep diaries will be completed. Monitor-wear logs will identify times the accelerometer is removed and the activity engaged in while the monitor is off. The photocell contained in the Actigraph GT3X-BT will be used to measure ambient light exposure. Accelerometers have been extensively used to assess children's physical activity (PA). Five days of monitoring had 0.8 reliability of accurately capturing the habitual PA of children. Activity counts captured in 5-second epochs will be categorized into sedentary, light, moderate, and vigorous PA using established cut points.

Since BMI can misrepresent adiposity among muscular and slender children, use of additional body fat indicators has been recommended. Investigators will assess percent body fat using Bod Pod.

The Automated Self-Administered 24-Hour Dietary Assessment Tool (ASA-24)174 will be used to assess children's dietary intake (e.g., total daily caloric intake, timing of intake, timing of the last eating episode of the day). As recommended, parents will complete the adult version of the ASA-24, providing proxy report of their child's dietary intake. Investigators will use 3 days of diet assessment as 3 days optimize the prediction of doubly labeled water estimated energy expenditure.

Comprehensive General Parenting Questionnaire (CGPQ) is a parent report of parenting practices among parents of 5-13 year olds. Investigators will assess subscales related to parenting structure (inconsistent discipline, consistency, organization, and scaffolding). There is support for the construct validity of the CGPQ. Parenting structure subscales have demonstrated acceptable to good internal reliability (ranging from .67-.74). Subscale scores range from 5 to 25. Higher scores indicate higher levels of structure.

The Bedtimes Routines Questionnaire (BRQ), is a 31-item parent report measure of children's bedtime routines, comprised of three scales measuring consistency of bedtime routines (weekday \& weekend), reactivity to changes in bedtime routines, and frequency of adaptive and maladaptive activities. The BRQ scales had good internal consistency ranging from α = 0.69 to 0.90. Scores on the consistency and adaptive behavior subscales range from 10 to 50 with higher scores reflecting more consistent bedtime routines and higher. The reactivity scale scores range from 5 to 25 with higher scores reflecting greater reactivity. The maladaptive behavior scale has possible scores ranging from 6 to 30 with higher scores reflecting more maladaptive behaviors.

How Children Spend their Summer (e.g., children's involvement in summer school, child care, entertainment programs, as well as day or overnight camps) will be assessed by a parent report survey based on a modified version of the Early Childhood Longitudinal Program Kindergarten Class' parent interview on summer activities. The Girl's Health Enrichment Multisite Studies demographic protocol will be employed with parents.

Perceived Stress Scale (PSS-10) is a 10-item self-report measure of perceived stress with established acceptable psychometric properties(α's >.70, test-retest criterion coefficient >.7, validated factor structure and evidence of convergent validity). Scores range from 0 to 40 with higher scores reflecting higher levels of perceived stress.

Interpersonal Support Evaluation List (ISEL) is a 12-item self-report measure of the perceived availability of social support (i.e. Tangible, appraisal, and belonging). The ISEL has demonstrated good reliability. The "tangible" subscale assesses perceived availability of resources and material aid; the "appraisal" subscale assesses the perceived availability of another individual(s) to discuss one's problems; the "self-esteem" subscale assesses the perceived availability of someone to compare one's self to in a positive manner; and the "belonging" subscale, the perceived availability of having others to socialize and do things with. Scores range from 0-30 on each scale with greater scores indicating higher levels of social support.

The Treatment Questionnaire Concerning Continued Program Participation was originally developed to assess reasons for continuing to participate in a weight-loss program. We have adapted it assess reasons for continuing to participate focused on addressing children's sleep during summer. Scores in the Autonomous Regulation scale range from 5 to 35 and scores on the Controlled Regulation range from 8 to 56. Higher scores reflect higher levels of Autonomous and Controlled regulation.