Abstract
STUDY OBJECTIVES: We investigated the moderation of caloric intake on the association between race/ethnicity and habitual sleep in adolescents. METHODS: We analyzed the data obtained from 324 adolescents who completed the follow-up examination of the Penn State Child Cohort study. We collected actigraphy-measured sleep duration on 7 consecutive nights and computed their mean and standard deviation as habitual sleep duration (HSD) and habitual sleep variability (HSV), respectively. We also measured participants' daily intakes of total calorie, total fat, carbohydrates, and protein, through the Youth/Adolescent Food Frequency Questionnaire. Adjusted mean HSD and HSV among non-Hispanic whites and racial/ethnic minorities were compared by using analysis of covariance (ANCOVA), while controlling for age, sex, BMI percentile, total caloric intake, and socioeconomic status. The significance of the interaction between race/ethnicity and caloric intake was further tested in ANCOVA models. RESULTS: The study sample consisted of 79.3% non-Hispanic whites, 13.0% African American, 4.6% Hispanics, 2.2% Asian, and 0.9% American Indian. Adolescents who are racial/ethnic minorities showed shorter HSD (mean (SE): 6.80 (0.10) vs. 7.07 (0.05) hours/night, p = 0.02) and higher HSV (mean (SE): 1.31 (0.07) vs. 1.15 (0.04) hours/night, p = 0.04) than non-Hispanic whites. Racial/ethnic differences in HSV were significantly more pronounced among adolescents with high caloric intake (p interaction = 0.01), especially from carbohydrates (p interaction = 0.03) and fat (p interaction = 0.05). CONCLUSION: Adolescents who are racial/ethnic minorities slept objectively shorter and with greater night-to-night variability than non-Hispanic whites. The racial/ethnic disparity in habitual sleep variability was more pronounced among adolescents with high caloric intake, particularly from carbohydrates and fat.