Association of Circadian Misalignment with Diet and Physical Activity in Adolescents

Circadian rhythms, particularly the sleep-wake cycle, food intake (FI) and physical activity (PA) are reciprocally synchronized. Lipid and carbohydrate metabolism pace depend on circadian stability. Timing, quality and quantity of FI and PA align circadian clocks. Therefore, circadian misalignment, which is highly prevalent in adolescents, is potentially impacting this triad. We examined whether subjective and objective metrics of circadian misalignment are associated with FI and PA in adolescents.

We assessed 377 adolescents from the Penn State Child Cohort (median 16 years; 46% female; 22% racial/ethnic minority) who had a minimum of 3-nights of at-home actigraphy (ACT) and a 9-h in-lab polysomnography (PSG). ACT-measured sleep midpoint (SM) was calculated as the central point of the sleep period, while sleep regularity (SR) was calculated as the intra-individual standard deviation of the SM. Circadian preference (CP) was measured with the Morningness-Eveningness Questionnaire. Bouts of sedentary behavior (SB) and level of SB and of moderate-to-vigorous PA (MVPA) were also derived from ACT. FI was measured via the Youth/Adolescent Food Frequency Questionnaire. PA and FI were dependent variables. Stepwise linear regression models adjusted for demographics (sex, race/ethnicity, age, BMI percentile), sleep disorders (insomnia, PSG-apnea/hypopnea index) and insufficient sleep (ACT-mean sleep duration, ACT-sleep duration variability).

A later SM was significantly associated with greater intake of carbohydrates (β=.125, p=.022), an association that was attenuated when adjusting for sleep variability (β=.094, p=.102). A later SM was also associated with greater bouts of SB, even when adjusting for all covariables (β=.167, p=.006). Neither SR nor CP were significantly associated with FI or PA in adolescents.

Adolescents with a delayed sleep phase are more likely to consume more carbohydrates and have greater number of periods of sedentary behavior. Circadian misalignment of the sleep-wake cycle, and its associated variability in sleep duration, should be an integral part of interventions targeting poor dietary choices and sedentarism in youth.