The sleep timing preferences and patterns of adolescent girls are linked to an increased risk for obesity, with weaker, albeit non-significant associations observed in boys, according to a study published today in JAMA Pediatrics.
Researchers from the Massachusetts General Hospital for Children and Harvard Medical School sought to examine the influence that sleep timing and preferences have on adolescent teens in relation to their risk of obesity and poor cardiometabolic health. In children, poor quality and short duration of sleep are known to contribute to increasing obesity and cardiometabolic risk.
The study examined 804 children, 418 girls and 386 boys, aged 12 to 17 years (mean age of 13.2 years) who were a part of Project Viva, a cohort study began by researchers at the Harvard Pilgrim Healthcare Institute 20 years ago; the project assessed Boston-area mothers and children to distinguish early-life factors that impact long-term health. Chronotypes (ie, whether someone is a night owl or early riser) were evaluated, as well as social jet lag, which assessed the sleep midpoint difference between weekends and weekdays:
- Obesity was measured through anthropometry and dual-energy x-ray absorptiometry
- Cardiometabolic risk score was examined in a subset of 479 adolescents who provided fastening blood samples
Results of the multivariable models adjusted for age, puberty, season, and sociodemographic revealed that associations of chronotype and social jet lag with obesity varied by sex. Boys revealed no definite associations, however, girls with greater evening preferences had a significantly heightened waist circumference (WC) (0.58-cm; 95% CI, 0.12-1.03 cm; P =.04) and fat mass index (FMI) (0.16 kg/m2; 95% CI, 0.01-0.31 kg/m2; P =.03). Social jet lag was additionally significant in girls as each hour attributed to a 1.19 cm (95% CI, 0.04-2.35 cm; P =.21) higher WC and a 0.45 kg/m2 (95% CI, 0.09-0.82 kg/m2; P =.01) higher FMI.
While boys exhibited no significant observations, the study noted that “observations were generally in the same direction as observed in girls,” said the authors. Cardiometabolic risk scores of both boys and girls also revealed no associations to chronotype or social jet lag in the subset.
As teens wake early during the weekdays for school, sleeping later in the evening creates irregular sleep schedules that may cause circadian misalignment. Senior study investigator Elsie Taveras, MD, division chief of general academic pediatrics, highlighted that “night owls, teenagers who prefer to go to bed late but have to get up early for school, had higher waist circumference and greater abdominal fat deposition than the ‘morning larks,’ those who prefer to go to bed early and get up early to begin their day,” said Taveras.
This increase in obesity risk stresses the need for consistent sleep-wake patterns throughout the week, which are further affected by differing weekday and weekend sleep patterns. Lead study author Elizabeth Cespedes Feliciano, ScD, recommended that “families should encourage consistency in their children’s sleep schedules and their bed and wake times as well as improvements in their sleep hygiene by limiting electronic media and caffeine use in the evening.”
By maintaining consistent sleep schedules throughout the week that limits evening chronotypes and social jet lag, adolescents can reduce obesity risk, especially within at-risk groups of adolescent girls and late-sleeping individuals.
Feliciano EMC, Rifas-Shiman SL, Quante M, et al. Chronotype, social jet lag, and cardiometabolic risk factors in early adolescence.[published online September 16, 2019]. JAMA Pediatrics. doi: 10.1001/jamapediatrics.2019.3089.