Sex differences in the association between sleep and body mass index in adolescents

OBJECTIVE: To determine whether an association between short sleep duration and increased body mass index (BMI) exists in a sample of U.S. adolescents. STUDY DESIGN: Public-use dataset of the National Longitudinal Study of Adolescent Health. Final sample included 4486 adolescents (51% female). Main outcome was BMI transformed into z-scores for age and sex using reference values from the Centers for Disease Control/National Center for Health Statistics. Overweight was defined as > or =95th percentile. Linear and logistic regression models were calculated. Sleep duration was self-reported in hours. A quadratic term for sleep was added to test curvilinear association. Covariates included age, race, parental education, activity and inactivity scores. RESULTS: Among males, linear regression indicated that sleep duration significantly predicted BMI z-score (Beta = -0.08, 95% CI: -0.12, -0.03). Logistic regression indicated that sleep duration predicted risk of overweight among males (OR = 0.90, 95% CI: 0.82, 1.00). Sleep duration was not a significant predictor among females in either regression model. Quadratic term for sleep was not significant for either sex. CONCLUSIONS: Longer sleep duration was weakly associated with lower BMI and risk of overweight among male adolescents only. This sex-related difference may be due to differences in the physiology of puberty or in sleep characteristics.     

Correlates of beverage intake in adolescent girls: the National Heart, Lung, and Blood Institute Growth and Health Study

OBJECTIVES: To examine longitudinal changes in consumption of 6 types of beverages (milk, diet and regular soda, fruit juice, fruit-flavored drinks, and coffee/tea) in girls and determine the relationship between beverage intake, body mass index (BMI), and nutrient intake. STUDY DESIGN: Three-day food diaries were included from black (1210) and white (1161) girls who participated in the National Heart, Lung, and Blood Institute Growth and Health Study. Diaries were recorded during annual visits beginning at ages 9 or 10 years until age 19 years. Mixed models estimated the association of (1) visit and race with average daily consumption of beverages and (2) beverage intake with BMI and average daily intake of total calories, sucrose, fructose, total sugars, and calcium. RESULTS: For girls of both races, milk consumption decreased and soda consumption increased with time. Changes in beverage intake with time varied by race for all beverages except fruit juice. For all beverage categories, consumption was associated with caloric intake. Of all beverages, increasing soda consumption predicted the greatest increase of BMI and the lowest increase in calcium intake. CONCLUSIONS: Public health efforts are needed to help adolescents gain access to and choose healthful beverages and decrease intake of beverages of minimal nutritional value.     

Neighborhood disadvantage as a risk factor for pediatric obstructive sleep apnea

OBJECTIVE: Low socioeconomic status (SES) is associated with a range of health outcomes. Our objective was to study the relationship between residence in a neighborhood of severe socioeconomic disadvantage and childhood obstructive sleep apnea (OSA). STUDY DESIGN: Cross-sectional analysis of 843 (49% female, 36% African-American) children 8 to 11 years of age from a community-based cohort. Data on neighborhood conditions were obtained from the 2000 US Census. The main outcome measure was OSA, defined as an obstructive apnea hypopnea index >5 events per hour or an obstructive apnea index >1 event per hour. RESULTS: Residence in a neighborhood of severe socioeconomic disadvantage was significantly associated with OSA after adjusting for effects of previously established risk factors: premature birth, obesity, and African-American ethnicity (OR = 3.44, 95% CI = 1.53-7.75). Secondary analyses showed that neighborhood disadvantage remained significantly associated with OSA: (1) in the African-American subgroup, after controlling for effects of prematurity and obesity; and (2) after controlling for indicators of household-level SES or other health characteristics. CONCLUSIONS: Childhood OSA is associated with low SES as measured by an index describing severe neighborhood disadvantage, emphasizing the potential importance of environmental factors, particularly those associated with neighborhood distress, as risk factors for OSA.