Sleep duration and timing are prospectively linked with insulin resistance during late adolescence

OBJECTIVE

The aim of this study was to evaluate whether short sleep duration or later sleep timing is a risk factor for insulin resistance (IR) in late adolescence.

METHODS

Mexico City adolescents enrolled in a longitudinal birth cohort (ELEMENT) took part in two study visits during peri-puberty that occurred approximately 2 years apart. IR was assessed with serum glucose and insulin. Four groups were defined using puberty-specific cut points: no IR over the follow-up period, transition from normal to IR, transition from IR to normal, and IR at both time points. Baseline sleep assessments were measured with 7-day wrist actigraphy. Multinomial logistic regression models were used to evaluate associations between sleep duration and timing with homeostatic model assessment of insulin resistance categories, adjusting for age, sex, and baseline pubertal status.

RESULTS

Adolescents who were ≥ 1 hour below the sleep duration recommendations-for-age were 2.74 times more likely to develop IR (95% CI: 1.0-7.4). Similarly, adolescents who were in the latest category of sleep midpoint (>4:33 a.m.) were more likely than those with earliest midpoints (1 a.m.-3 a.m.) to develop IR (odds ratio = 2.63, 95% CI: 1.0-6.7). Changes in adiposity over follow-up did not mediate sleep and IR.

CONCLUSIONS

Insufficient sleep duration and late sleep timing were associated with development of IR over a 2-year period in late adolescence.

0201 Sleep duration and timing is prospectively linked with increases in insulin resistance over late adolescence

Introduction

During puberty, adolescents experience a period of transient insulin resistance (IR) that normalizes upon full maturation. Yet, IR continues to rise for some adolescents, increasing metabolic disease and type 2 diabetes risk in adulthood. Whether short sleep duration and/or later sleep timing are risk factors for persistently increasing IR in late adolescence has not been explored.

Methods

The study population includes 362 adolescents from Mexico City enrolled in a longitudinal birth cohort (ELEMENT study). Beginning in 2015, when participants were between the ages of 9 and 17, there were 2 clinic visits that occurred approximately 2 years apart. During the visit, a fasting blood sample and anthropometric measurements were taken. Insulin resistance was assessed with glucose and insulin via HOMA-IR. Four groups were defined using puberty-specific cutpoints for IR: normal HOMA-IR over the follow-up period (reference), transition from normal to IR, transition from IR to normal, and IR at both time points. Baseline sleep assessments (sleep duration, timing, and variability of both duration and timing) were measured with 7-day actigraphy. Multinomial logistic regression models were used to evaluate associations between sleep duration and timing with HOMA-IR categories, adjusting for age, sex, and baseline pubertal status

Results

Seventeen percent of the sample developed insulin resistance over the follow-up period. Adolescents ≥1 hour below the sleep duration recommendations-for-age were over twice as likely to be in the group that developed IR compared to the normal group (95% CI 1.1, .9; P for trend=0.03). Similarly, adolescents who had a sleep midpoint later than 4:36 AM were 2.77 times as likely to be in the increasing HOMA-IR category (95% CI 1.0, 7.5; P for trend=0.05). Interestingly, there was no evidence that changes in adiposity over follow-up mediated associations between sleep and insulin resistance.

Conclusion

Insufficient sleep duration and late sleep timing were independently associated with development of IR over a 2-year period in peri-puberty. Adequate sleep during the pubertal period may promote metabolic health into young adulthood, independent of any changes in adiposity.

Support (If Any)

Dr. Jansen is supported by K01HL151673. The study is supported by P01 ES02284401.

Adolescent sleep timing and dietary patterns in relation to DNA methylation of core circadian genes: a pilot study of Mexican youth

Mistimed sleep/wake and eating patterns put shift workers at increased risk for cardiometabolic disease, and epigenetic modification of circadian genes has been proposed as a mechanism. Although not as extreme as shift workers, adolescents often have delayed sleep timing and irregular eating patterns. The aim was to assess whether sleep midpoints - median of bed and wake time - and dietary patterns in adolescents were associated with DNA methylation of circadian genes. The study population included 142 Mexican youth (average age of 14.0 (SD = 2.0) years, 49% male). Average sleep midpoint over weekdays was estimated with actigraphy. Diet was assessed with a semi-quantitative food frequency questionnaire, and three dietary patterns were derived from principal component analysis, a Plant-based & lean proteins pattern, a Meat & starchy pattern, and an Eggs, milk & refined grain pattern. DNA methylation was quantified in blood leukocytes with the Infinium MethylationEPIC BeadChip, and data from 548 CpG sites within 12 circadian genes were examined. Linear regression analyses, adjusted for sex, age, and % monocytes, showed that later sleep timing was associated with higher DNA methylation of several circadian genes, notably with RORB, PER1, CRY2, and NR1D1. Each of the dietary patterns examined was also related to circadian gene DNA methylation, but the Eggs, milk & refined grain pattern ('breakfast' pattern) had the clearest evidence of relationships with circadian genes, with inverse associations (lower DNA methylation) across all 12 genes. Findings suggest that timing-related sleep and eating behaviours among adolescents could result in epigenetic modification of clock genes.

0027 Adolescent Sleep Timing And Dietary Patterns In Relation To Dna Methylation Of Core Clock Genes

Introduction

Mistimed sleep/wake and eating patterns put adult shift workers at increased risk for chronic disease, and epigenetic modification of core clock genes has been proposed as a mechanism. Although not as extreme as shift workers, adolescents often have delayed sleep timing. Our aim was to assess whether sleep midpoints in adolescents are associated with DNA methylation of circadian genes. A secondary aim was to examine associations between dietary patterns and circadian gene methylation.

Methods

The study population included 142 Mexican youth (average age 14.0 (SD=2.0) years, 49% male) enrolled in a cohort study. Average sleep midpoint (between bed time and wake time) over 7 days was estimated with actigraphy. Diet was assessed with a semi-quantitative food frequency questionnaire, and three dietary patterns were derived from principal components analysis (a vegetable-based pattern, a meat and starch-based pattern, and a breakfast pattern). DNA methylation was quantified in blood leukocytes with the Infinium MethylatinEPIC BeadChip. We selected 166 loci (CpG sites) within CpG islands of core ‘clock’ genes known to regulate circadian rhythms (CLOCK, BMAL, PER1, PER2, PER3, CRY1, CRYI2, RORA, RORB, REV-VERBA, REV-VERBB). Linear regression was used to analyze associations between sleep midpoint or dietary patterns and logit-transformed percent methylation at the 166 CpG sites. All models were adjusted for sex and age.

Results

The average midpoint was 3:41 AM (SD=1 hr 15 min); average bed time was 11:29 PM (SD=68 min) and average wake time was 7:53 AM (SD=97 min). Sleep midpoint was positively associated with DNA methylation of CpG sites from the genes REV-VERBA and RORB at the Bonferroni-corrected significance level of p<0.005. The breakfast dietary pattern (rich in eggs, milk, and bread) was inversely associated with DNA methylation at RORA (P=0.003).

Conclusion

Sleep timing and dietary habits are associated with DNA methylation of core clock genes in adolescents. Epigenetic modification of clock genes could in part underlie relationships between sleep, diet, and metabolic health among adolescents.

Support (If Any)

Dr. Jansen is supported by the NIH/NHLBI grant 5T32HL110952-05.

Emerging issues in public health genomics

This review highlights emerging areas of interest in public health genomics. First, we describe recent advances in newborn screening (NBS), with a focus on the practice and policy implications of current and future efforts to expand NBS programs (e.g., via next-generation sequencing). Next, we detail research findings from the rapidly progressing field of epigenetics and epigenomics, highlighting ways in which our emerging understanding in these areas could guide future intervention and research efforts in public health. We close by considering various ethical, legal, and social issues posed by recent developments in public health genomics; these include policies to regulate access to personal genomic information, the need to enhance genetic literacy in both health professionals and the public, and challenges in ensuring that the benefits (and burdens) of genomic discoveries and applications are equitably distributed. We also note needs for future genomic research that integrates across basic and social sciences.