In their analysis of the Acute Stroke Registry and Analysis of Lausanne (ASTRAL) and University Hospital of Bern stroke registries, Dr. Hajdu et al. observed a temporal effect of endovascular treatment on outcomes of patients with acute large vessel occlusion. Specifically, patients treated with endovascular thrombectomy between 8 and 11 am were at greater odds of achieving clinical improvement (as determined by a shift in the modified Rankin Scale) when compared with patients treated during other time intervals, whereas patients treated in the late afternoon and early evening were at lower odds of a better functional outcome. These observations were found despite multivariable modeling, including adjustment for delay from symptom onset to endovascular start time, which could have mediated this effect. Dr. Aristizabal-Carmona and colleagues argue that certain physiologic elements, which vary throughout the day, may contribute to this effect on outcomes associated with severe stroke. Whether the effect of treatment time of day is modifiable remains an open question.