Abstract Body: Time restricted feeding (TRF), or food consumption restricted to <10 hrs/day, has been shown to improve blood pressure in various cardiometabolic diseases, yet there is limited data on the effect in SS hypertension. The goal of this study was to examine the effect of TRF on disease development in the Dahl SS rat. We hypothesized that implementing TRF during a critical timepoint in disease progression would reduce mean arterial blood pressure (MAP). To study this, femoral catheters were surgically implanted in male Dahl SS rats at 9±0.5 weeks of age (n=5-7/group), allowing for urine and arterial blood sample collection from conscious rats during continual blood pressure recording. After 1 week of recovery, rats either continued a low salt (LS;0.4% NaCl) diet or were switched to a high salt diet (HS;4% NaCl) with ad libitum (ad lib) access for 1 week. At the start of week 2, a subset of rats began TRF, in which food was provided for 8 hrs (10PM-6AM) during their active period for an additional week. Rats meeting the following criteria were included in analysis: pulse pressure > 10 mmHg, baseline MAP of 115-130 mmHg, and a 10-20 mmHg increase in MAP after 1 week on HS. Differences in MAP were analyzed by 2-way ANOVA with Tukey multiple comparisons and data are reported as mean ± SEM. By the end of week 2, HS TRF rats trended toward lower average MAP compared to HS ad lib rats (141.51±3.41 vs 149.49±1.65 mmHg; p=0.07). However, we found that the HS TRF rats had reduced MAP during their active period (6PM-6AM), compared to the HS ad lib rats (142.60±2.99 vs 151.65±1.862 mmHg; p<0.05), but no difference during the inactive period (6AM-6PM). At the end of the study, average MAP was calculated every 4 hrs to identify the timing at which TRF reduced MAP. We found that the HS TRF rats had lower MAP from 6PM to 10PM (134.61±2.34 vs 146.75±1.21 mmHg; p<0.05) and 10PM to 2AM (144.58±2.79 vs 154.70±2.18 mmHg; p<0.05) when compared to the HS ad lib rats. The LS TRF group also had lower pressure from 6PM-10PM compared to the LS ad lib group (124.93±1.19 vs 130.56±0.73 mmHg; p<0.05), suggesting that this time-specific reduction in MAP may be due to fasting, as there were no other differences in MAP within the LS groups. This suggests that TRF may slow progression of hypertension development in the Dahl SS rat, primarily by affecting MAP during the active period. Future studies will examine how TRF affects Na⁺ handling to further understand these time-dependent effects.