Abstract Body (Do not enter title and authors here): Introduction: Short sleep duration is associated with increased cardiometabolic risk. Studies suggest that sleep deprivation may alter
DNA-methylation patterns involved in cardiometabolic health. However, most findings are from acute sleep deprivation or short duration
studies.
Hypothesis: Prolonged sleep restriction mimicking real-life situation is associated with differentially methylated CpG loci (DML) in the core clock candidate genes and across the epigenome in an epigenome-wide association study (EWAS).
Methods: Sixty participants (65% women) aged 21-73 y were included in randomized crossover studies with 2 phases of 6 weeks each. Phases differed in sleep duration: adequate sleep (AS; sleep ≥7h/night) or sleep restriction (SR; -1.5h/night relative to AS). DNA was isolated from whole blood at wk 0 and 6 of each phase. DNA methylation (DNAm) was quantified the Illumina Infinium MethylationEPIC BeadChip array v.2.0 (>900K methylation sites) and Partek Genomic Suite v.720.0831. After quality control and normalization, several global and stratified EWASs were performed to test the impact of sleep condition on DNAm. Analyses were adjusted for week, phase, sex, age, BMI and cell type composition. We also focused on methylation changes of the selected core-clock candidate genes (RORA, CRY1, NR1D2, TIMELESS, NPAS2, NFIL3, RORB, PER3, CSNK1E, ARNTL2, CRY2, CLOCK, ARNTL, RORC, PER2, BHLHE40, NR1D1, CSNK1D, BHLHE41 and PER1).
Results: In the candidate gene approach, we detected several significant DML. Top-ranked DML in selected core clock genes with significant interactions between condition and time were: cg02394126 at ARNTL (p<0.001), cg23506964 at CLOCK (p=0.001), cg03701037 at NPAS2 (p=0.009), cg06606972 at NPAS2 (p=0.009), and cg13576304 at RORA (p=0.008). Hypermethylation was primarily observed after 6 wk of SR vs AS for cg02394126, cg23506964, cg03701037, and cg06606972, while hypomethylation was observed for cg13576304 (RORA). In EWAS, we detected some condition x time interactions in cg23738833 at SNHG3-RCC1 (p=1,34E-06), cg13280380 in the FAF1 gene (p=2,25E-05), cg03179866 in the MMP12 gene (p=2,78E-05), and cg13063696 (p=3,21E-05). All but cg23738833 (SNHG3-RCC1) showed hypermethylation after 6 wk of SR vs AS.
Conclusion: Six weeks of mild SR was associated with changes in DNAm in core-clock candidate genes and in other genes in the EWAS. However, further studies are needed to confirm these findings and determine the functional pathways.