I'm going to go to sleep when I am talking to a friend.
Why would you fall asleep while talking to a friend?
The friend I'm talking to makes me very sleepy.
It's impolite to fall asleep during a conversation. You should let your friend know that you're sleepy and have the conversation another time. If you fall asleep it might hurt their feelings.
I don't want to hurt their feelings, but the alternative is not talk to them which would hurt them more.
That's a tough predicament. Maybe try drinking coffee or tea when talking to them, so as to not fall asleep?