I slept, how should I respond to the professor? It was late at night I sent an email to my professor. due to time differences, it was early over there. After sending an email I slept and my professor responds me and askeS me to skype in 2 hours. I slept and I didn't even open the email. How can I ask a meeting?
I didn't know he would ask me to have a skype, (in 2 hours after sending the mail):-O

could you please tell me how to respond my professor?
Students are allowed to sleep at night. In all likelihood the prof just forgot about the differences in timezone, or miscalculated the time difference.  Just answer something like :

Dear prof. XXX,

Sorry I missed your reply. It was 22:00 hours when I sent that message, and went to sleep immediately afterwards. Could we make another Skype appointment?

Best,
YYY