Figure 2.

Environmental circadian disruption (ECD) accelerates time to stroke onset. Chronic phase advances of the light-cycle accelerated time to stroke onset without diverging systolic or diastolic blood pressure readings. Log-rank (Mantel–Cox) test survival analysis showed (P < 0.05) with a median survival of the control group (n = 12 rats) of 93.5 days to phase-advanced group (n = 12 rats) of 81.50 days (A). Body weight between the 2 groups (B) showed no significance [P = 0.6129; F(1,10) = 0.2727]. The phase advancing group (n = 3 rats; M = 194.2) compared with the control group (n = 3 rats; M = 204.6) difference between means (SE = −10.41 ± 2.921) demonstrated a significant attenuation of systolic blood pressure (SBP) rise during chronic phase advancing toward the end of the experiment (t = 3.565, df = 126, P = 0.0005) (C). However, diastolic blood pressure (DBP) was not significantly different between the 2 groups at any point (D). Dotted lines indicate shift day for rats in phase-advancing light conditions. Dashed red line indicates the point at which water was switched to 1% salt water for all animals.