I Just Started Clonazepam Today--1/2 A Dose Of 0.5 Mg

I just started Clonazepam today--1/2 a dose of 0.5 mg twice a day. I have only taken 1/2 today so far. I am taking it for anxiety. It has made me very sleepy. I need to go back to work soon and have to drive very far. Would it be okay to just take 1/4 of the pill? I am very sensitive to medicines. Also would it be better to take it at night?