As per preclinical data, ischemic stroke progression shows circadian variation, with rodent models exhibiting more active cell death and infarct growth with inactive phase (daytime) than active phase (nighttime) stroke onset. Researchers herein conducted a Korean nationwide multicenter observational cohort study with the aim to evaluate the effects of stroke onset time on presenting severity, early neurological deterioration (END), and long-term functional outcome in human ischemic stroke.

• A total of 17,461 consecutive patients with ischemic stroke were included; 2,219 (12.7%) patients had occurrence of END.

• During the first 72 hours following symptom onset, a greater clinical severity, and a higher likelihood of experiencing early neurologic worsening were recorded for patients with night-onset stroke.

• In addition, patients with night-onset stroke less frequently had favorable 3-month global disability outcomes than day-onset stroke patients.