Longitudinal Assessment of Sleep Trajectories during Early Childhood and Their Association with Obesity.

Introduction: To identify longitudinal sleep trajectories in early childhood and examine the influence of sleep duration on obesity risk via BMI percentile (BMIp). Methods: Sleep, physical activity, and television viewing were measured in a cohort of 301 children, starting in 2001-2002, when children were 3 years and followed them through age 6. Nighttime sleep, daytime naps, and sleep duration were calculated. A series of latent growth curve models were used to estimate predictors of rate of change in sleep duration and BMIp overtime. A parallel process latent growth model examined the longitudinal relationship between sleep duration and BMIp simultaneously. Results: Most children (>80%) slept >10 hours per night across ages 3 to 6 years, despite the majority of children (>66%) having bedtimes after 9 pm. Sleep duration decreased on average by 0.22 (95% CI 0.20-0.24) hours each year of age (p < 0.001), while BMIp increased on average by 1.76 (95% CI 1.18-2.34) each year of age (p < 0.001). Baseline sleep duration predicted the BMIp slope factor, over and above strong effects of baseline BMIp. This indicated that greater sleep duration at baseline was predictive of decreased BMIp over time (unstandardized coefficient = -1.52 (95% CI 0.34-2.71, p = 0.012). Conclusions: Longer sleep duration at age 3 predicted decreased BMIp from ages 3 to 6. These findings indicate that focusing on sleep behaviors in children before age 3 may be a priority for pediatric providers with a goal of decreasing obesity risk.

Sleep & Circadian Health are Associated with Mood & Behavior in Adolescents with Overweight/Obesity.

OBJECTIVE/BACKGROUND: Rates of overweight/obesity and insufficient/delayed sleep are high among adolescents and are also unique risk factors for mood/behavior difficulties. This study aimed to evaluate relationships between sleep/circadian health and mood/behavior in a cohort of adolescents with overweight/obesity. PARTICIPANTS: Twenty-two adolescents (16.4 ± 1.1 years) with overweight/obesity attending high school completed in the study. METHODS: Participants completed one week of home sleep monitoring (actigraphy), questionnaires assessing chronotype (diurnal preference; Morningness/Eveningness Scale for Children) and mood/behavior (Strengths & Difficulties Questionnaire), and had in-laboratory salivary melatonin sampling on a Thursday or Friday during the academic year. RESULTS: Linear regressions revealed later weekday bedtime and shorter weekday time in bed and sleep duration were associated with worse mood/behavior scores. Shorter duration of melatonin secretion and greater "eveningness" were also associated with worse mood/behavior scores. CONCLUSIONS: Short and late sleep, shorter melatonin secretion, and eveningness chronotype are associated with worse mood/behavior symptoms in a cohort of adolescents with overweight/obesity. Clinicians should assess for both sleep and mood/behavior symptoms and further research is needed to evaluate the impact of improved sleep on mood/behavior in adolescents with overweight/obesity.

Too Late and Not Enough: School Year Sleep Duration, Timing, and Circadian Misalignment Are Associated with Reduced Insulin Sensitivity in Adolescents with Overweight/Obesity.

OBJECTIVES: To examine the relationship between insulin resistance (IR) and sleep/circadian health in overweight/obese adolescents. We hypothesized that insufficient and delayed sleep would be associated with IR in this population. STUDY DESIGN: Thirty-one adolescents (mean age, 16.0 ± 1.4 years; 77% female) with body mass index ≥90th percentile for age/sex were recruited from outpatient clinics at a children's hospital. Participants underwent 1 week of objective home sleep monitoring with wrist actigraphy during the academic year. A 3-hour oral glucose tolerance test was conducted, followed by in-laboratory salivary dim-light melatonin sampling every 30-60 minutes from 5 p.m. to noon the next day. Regression analyses between sleep and circadian variables with IR were examined. RESULTS: Longer sleep time and time in bed on weekends and weekdays and earlier weekday bedtime were significantly associated with better insulin sensitivity. Participants who obtained less than the median duration of sleep per night (6.6 hours) had evidence of IR with compensatory insulin secretion compared with those obtaining ≥6.6 hours of sleep. A wider phase angle between bedtime and melatonin onset, indicating a later circadian timing of sleep onset, was significantly associated with IR. CONCLUSIONS: Short sleep duration, later weekday bedtime, and later circadian timing of sleep were associated with IR in a cohort of adolescents with overweight/obesity during the school year. Further research is needed to better understand the physiology underlying these observations and to evaluate the impact of improved sleep and circadian health on metabolic health in this at-risk population.

Predictors of Infant Body Composition at 5 Months of Age: The Healthy Start Study.

OBJECTIVE: To examine associations of demographic, perinatal, and infant feeding characteristics with offspring body composition at approximately 5 months of age. STUDY DESIGN: We collected data on 640 mother/offspring pairs from early pregnancy through approximately 5 months of age. We assessed offspring body composition with air displacement plethysmography at birth and approximately 5 months of age. Linear regression analyses examined associations between predictors and fat-free mass, fat mass, and percent fat mass (adiposity) at approximately 5 months. Secondary models further adjusted for body composition at birth and rapid infant growth. RESULTS: Greater prepregnant body mass index and gestational weight gain were associated with greater fat-free mass at approximately 5 months of age, but not after adjustment for fat-free mass at birth. Greater gestational weight gain was also associated with greater fat mass at approximately 5 months of age, independent of fat mass at birth and rapid infant growth, although this did not translate into increased adiposity. Greater percent time of exclusive breastfeeding was associated with lower fat-free mass (-311 g; P < .001), greater fat mass (+224 g; P < .001), and greater adiposity (+3.51%; P < .001). Compared with offspring of non-Hispanic white mothers, offspring of Hispanic mothers had greater adiposity (+2.72%; P < .001) and offspring of non-Hispanic black mothers had lower adiposity (-1.93%; P < .001). Greater adiposity at birth predicted greater adiposity at approximately 5 months of age, independent of infant feeding and rapid infant growth. CONCLUSIONS: There are clear differences in infant body composition by demographic, perinatal, and infant feeding characteristics, although our data also show that increased adiposity at birth persists through approximately 5 months of age. Our findings warrant further research into implications of differences in infant body composition.

Maternal obesity, gestational weight gain, and offspring adiposity: the exploring perinatal outcomes among children study.

OBJECTIVE: To determine whether adequate vs excessive gestational weight gain (GWG) attenuated the association between maternal obesity and offspring outcomes. STUDY DESIGN: Data from 313 mother-child pairs participating in the Exploring Perinatal Outcomes among Children study were used to test this hypothesis. Maternal prepregnancy body mass index (BMI) and weight measures throughout pregnancy were abstracted from electronic medical records. GWG was categorized according to the 2009 Institute of Medicine criteria as adequate or excessive. Offspring outcomes were obtained at a research visit (average age 10.4 years) and included BMI, waist circumference (WC), subcutaneous adipose tissue (SAT) and visceral adipose tissue, high-density lipoprotein cholesterol, and triglyceride levels. RESULTS: More overweight/obese mothers exceeded the Institute of Medicine GWG recommendations (68%) compared with normal-weight women (50%) (P < .01). Maternal prepregnancy BMI was associated with worse childhood outcomes, particularly among offspring of mothers with excessive GWG (increased BMI [20.34 vs 17.80 kg/m(2)], WC [69.23 vs 62.83 cm], SAT [149.30 vs 90.47 cm(2)], visceral adipose tissue [24.11 vs 17.55 cm(2)], and homeostatic model assessment [52.52 vs 36.69], all P < .001). The effect of maternal prepregnancy BMI on several childhood outcomes was attenuated for offspring of mothers with adequate vs excessive GWG (P < .05 for the interaction between maternal BMI and GWG status on childhood BMI, WC, SAT, and high-density lipoprotein cholesterol). CONCLUSION: Our findings lend support for pregnancy interventions aiming at controlling GWG to prevent childhood obesity.