The goal of this clinical trial is to learn about using the latest transcranial alternating current stimulation (tACS) to reduce the incidence of delirium in patients with subarachnoid hemorrhage. The main question it aims to answer is: • To evaluate the effect of tACS on reducing delirium in patients with subarachnoid hemorrhage. Participants will treated with real tACS or sham tACS. Researchers will mainly compare the two groups to see if patients' delirium will reduce by using tACS.