Vascular function studies in thoracic aortas were conducted with cumulative concentration–response curves of Ach, SNP, PE, and KCl. Ach-induced vascular relaxation during the light and dark phases is shown (A and B), along with (C) E_max and (D) EC_50. PE-induced vasoconstriction curves in the light and dark phases are shown (E and F), along with (G) AUC and (H) EC₅₀. Two-way ANOVA was used to compare diet and time of feeding during the light or dark period (^††P < 0.05 HFD and HFD+TRF light vs. HFD and HFD+TRF dark). Three-way ANOVA was used to compare diet, time of feeding, and time of day with Holm-Šídák post hoc test (n = 5–10, *P < 0.05; ^£P < 0.05 light vs. dark). Main effects and interactions are shown below graphs. (I) Aortic stiffness was assessed with PWV measurements between ZT2 and ZT5 in a separate cohort of mice. Two-way ANOVA was used to compare diet and time of feeding (n = 4–12, *P < 0.05). (M) A different cohort of mice sacrificed at ZT17 was used for histological analysis. Aortic vascular remodeling is shown with representative images, scale bar = 20 μm. Representative aortic cross sections were stained with H&E, and aortic wall thickness, an index of medial hypertrophy, was measured (J). Changes in wall thickness are indicated with a black line. (N) Representative aortic sections were stained with Masson’s trichrome, and (K) fibrosis was quantified in the 4 groups of mice. (O) Representative aortic cross sections were stained with Picrosirius red. (P) Picrosirius red–stained sections were examined under polarized light for (L) quantification of collagen I and III content. Two-way ANOVA was used to compare diet and time of feeding (n = 4–6, *P < 0.05).