Racial/ethnic disparity in habitual sleep is modified by caloric intake in adolescents

Edward O. Bixler, PhD: from the Apollo project and chimpanzees to sleep epidemiology

What an honor to write about Dr. Edward O. Bixler's contributions to the sleep field. In 1967, Dr. Bixler published a case report on a chimpanzee with implanted brain electrodes while working at an Air Force base in New Mexico. A few years later, in 1971, he published on the sleep effects of flurazepam in individuals with insomnia together with Dr. Anthony Kales, data that he had collected when the Sleep Research & Treatment Center (SRTC) was housed at the University of California Los Angeles. Dr. Bixler, a meticulous scientist, learned from Dr. Kales, a devoted clinician, to study "the whole patient, and all aspects of sleep," a legacy that continued when the SRTC moved to Penn State in Hershey. Indeed, Dr. Bixler's tenure at Penn State from 1971 until 2019 kept the science of the SRTC focused on that premise and helped translate scientific evidence into clinical care. He not only contributed early to the pharmacology of sleep and the effects of hypnotics, but he was also a pioneer in "sleep epidemiology." His "Prevalence of sleep disorders in the Los Angeles metropolitan area" study of 1979 was the first rigorous epidemiological study on sleep disturbances. Starting in 1990, he established the Penn State Adult Cohort to estimate the prevalence and natural history of sleep-disordered breathing and other sleep disorders in adults. Inspired by life-course epidemiology, he established in 2001 the Penn State Child Cohort to estimate the same phenomena in children. This Living Legend paper captures and highlights Dr. Bixler's enduring legacy to sleep science.

Short-term and intermediate-term fine particulate air pollution are synergistically associated with habitual sleep variability in adolescents - A cross-sectional study

BACKGROUND

Both air pollution and poor sleep have been associated with increased risk of cardiovascular diseases. However, the association between air pollution and sleep health, especially among adolescents, is rarely investigated.

METHODS

To investigate the association between fine particulate (PM2.5) air pollution and habitual sleep patterns, we analyzed data obtained from 246 adolescents who participated in the Penn State Child Cohort follow-up examination. We collected their individual-level 24-h (short-term) PM2.5 concentration by using a portable monitor. We estimated their residential-level PM2.5 concentration during the 60-day period prior to the examination (intermediate-term) using a kriging approach. Actigraphy was used to measure participants' sleep durations for seven consecutive nights. Habitual sleep duration (HSD) and sleep variability (HSV) were calculated as the mean and SD of the seven-night sleep duration. Multivariable-adjusted linear regression models were used to assess the association between PM2.5 exposures and HSD/HSV. An interaction between short-term and intermediate-term PM2.5 was created to explore their synergistic associations with HSD/HSV.

RESULTS

Elevated short-term and intermediate-term PM2.5 exposure were significantly (p < 0.05) associated with higher HSV, but not HSD. Specifically, the mean (95% CI) increase in HSV associated with 1 SD higher 24-h (26.3 μg/m3) and 60-day average (2.2 μg/m3) PM2.5 were 14.6 (9.4, 14.8) and 4.9 (0.5, 9.2) minutes, respectively. In addition, there was a synergistic interaction (p = 0.08) between short-term and intermediate-term PM2.5 exposure on HSV, indicative that the association between intermediate-term PM2.5 and HSV became stronger as short-term PM2.5 increases, and vice versa.

CONCLUSION

Short-term individual-level and intermediate-term residential-level PM2.5 exposures are adversely and synergistically associated with increased sleep variability, an indicator of instability of sleep quantity, in adolescents. Through such an association with sleep pattern, PM2.5 air pollution may increase long-term cardiometabolic risks.

Sleep variability and regularity as contributors to obesity and cardiometabolic health in adolescence

OBJECTIVE

Adolescence is a developmental stage of critical changes in sleep and its circadian timing when the contribution of abnormal sleep variability (amount) and sleep regularity (timing) to obesity and its associated adverse cardiometabolic health outcomes appears to increase. The aim of this study was to summarize findings from studies conducted in adolescents examining both sleep variability and regularity in relation to obesity and cardiometabolic health. Gaps in research and potential causal pathways that future studies should examine are highlighted.

RESULTS

Nightly deviations in sleep duration and sleep midpoint appear to contribute to the development of obesity and associated adverse cardiometabolic outcomes in youth. Studies show that increased sleep variability and irregularity are associated with obesity, decreased physical activity, dysregulated eating and inadequate diet, metabolic dysfunction, impaired cardiac autonomic balance, and elevated blood pressure in adolescents.

CONCLUSIONS

A stable circadian timing of sleep is essential to the overall physical well-being of youth. Emerging evidence supports that sleep variability and circadian misalignment, including sleep irregularity, contribute to adverse obesity-related health outcomes early on in adolescence. Future studies should focus on the underlying behavioral and biological mechanisms in the causal pathway between day-to-day deviations in the amount and timing of sleep and obesity.

Acute Impact of Fine Particulate Air Pollution on Cardiac Arrhythmias in a Population‐Based Sample of Adolescents: The Penn State Child Cohort

Background

Fine particulate (fine particles with aerodynamic diameters ≤2.5 μm [PM 2.5 ]) exposure has been associated with a risk of cardiac arrhythmias in adults. However, the association between PM 2.5 exposure and cardiac arrhythmias in adolescents remains unclear.

Methods and Results

To investigate the association and time course between PM 2.5 exposure with cardiac arrhythmias in adolescents, we analyzed the data collected from 322 adolescents who participated in the PSCC (Penn State Child Cohort) follow‐up examination. We obtained individual‐level 24‐hour PM 2.5 concentrations with a nephelometer. Concurrent with the PM 2.5 measure, we obtained 24‐hour ECG data using a Holter monitor, from which cardiac arrhythmias, including premature atrial contractions and premature ventricular contractions (PVCs), were identified. PM 2.5 concentration and numbers of premature atrial contractions/PVCs were summarized into 30‐minute‐based segments. Polynomial distributed lag models within a framework of a negative binomial model were used to assess the effect of PM 2.5 concentration on numbers of premature atrial contractions and PVCs. PM 2.5 exposure was associated with an acute increase in number of PVCs. Specifically, a 10 μg/m 3 increase in PM 2.5 concentration was associated with a 2% (95% CI, 0.4%–3.3%) increase in PVC counts 0.5 to 1.0, 1.0 to 1.5, and 1.5 to 2.0 hours after the exposure. Cumulatively, a 10 μg/m 3 increment in PM 2.5 was associated with a 5% (95% CI, 1%–10%) increase in PVC counts within 2 hours after exposure. PM 2.5 concentration was not associated with premature atrial contraction.

Conclusions

PM 2.5 exposure was associated with an acute increased number of ventricular arrhythmias in a population‐based sample of adolescents. The time course of the effect of PM 2.5 on ventricular arrhythmia is within 2 hours after exposure.

Sleep duration and eating behaviours among adolescents: a scoping review

INTRODUCTION

In the past decade, investigations of the relationship between sleep duration and eating behaviours have been emerging; however, a formal synthesis of the literature focussed on adolescent populations has not yet been conducted. We conducted a scoping review of the literature examining the relationship between sleep duration and eating behaviours in adolescents. Gaps in the research and directions for future research were identified based on the findings.

METHODS

A systematic search was employed on four research databases: PubMed, PsycInfo, CINAHL and Scopus; relevant grey literature was also reviewed. Studies that reported on the relationship between sleep duration and eating behaviours among high school-aged adolescents were included in the review. Data were extracted, charted and synthesized into a narrative. Consistent with the purpose of a scoping review, the methodological quality of the studies was not appraised. Stakeholders were consulted to validate the findings and provide insight into the interpretation and identification of pressing gaps in the research that remain to be addressed.

RESULTS

In total, 61 studies published between 2006 and 2021 met the criteria for review. Existing research focussed heavily on examining sleep duration in relation to intake of food from certain food groups, beverages and processed foods, and relied on a population study design, cross-sectional analyses and self-report measures.

CONCLUSION

Future research is needed to understand the link between sleep duration and eating-related cognition, eating contexts and disordered eating behaviours in order to better understand how ensuring sufficient sleep among adolescents can be leveraged to support healthier eating practices and reduce diet-related risks.

The Association between Postpartum Practice and Chinese Postpartum Depression: Identification of a Postpartum Depression-Related Dietary Pattern

Conflicting results of Chinese traditional postpartum practices have aroused concerns over their health effects. The role of postpartum practices in postpartum depression (PPD) is still a matter of discussion, especially from a dietary practice point of view. The current study was designed to (1) explore the association between postpartum practices and PPD, (2) to identify the dietary pattern related to PPD, and (3) to identify the possible pathways among postpartum practices and PPD. This study is part of the YI Study, which was a cross-sectional study conducted in 10 cities in China. Data for 955 postpartum women were used in the current analysis. The Edinburgh Postnatal Depression Scale (EPDS-10) was used to evaluate PPD with a cutoff value of 9. Postpartum practice was based on the participants’ self-reported practices. Individual practices were recorded and categorized as dietary and non-dietary practices. The dietary pattern was identified based on the food intake frequencies of 25 food groups using the method of reduced rank regression. Structural equation modeling was used to explore the potential pathways between postpartum practices and PPD. The current study observed significant associations between postpartum practices and PPD (Adjusted OR = 1.41, 95% CI: 1.04–1.90). A similar trend was also found between dietary postpartum practices and PPD (Adjusted OR = 1.39, 95%CI: 1.03–1.88) but not for non-dietary practices and PPD (Adjusted OR = 1.26, 95%CI: 0.92–1.75). A PPD-related dietary pattern was identified with the characteristics of a high intake of meat and eggs and a lower intake of vegetables, mushrooms, and nuts. This dietary pattern was significantly associated with a higher chance of adhering to postpartum practice (Adjusted OR = 1.26, 95% CI: 1.10–1.44). Based on the pathway analysis, this study also observed the association between postpartum practices and PPD, and the association between dietary practices and PPD were both mediated by sleep quality. In conclusion, this study demonstrated that a substantial proportion of women in modern China experience traditional postpartum Chinese practices and that either overall or dietary-related postpartum practices are associated with a higher risk of PPD. The current dietary practices in postpartum rituals may play an important role in developing PPD. A culturally embedded, science-based dietary guideline is required to help women to achieve both physical and psychological health in the postpartum period.