My LO always fall asleep during feeding

Is it normal that 1 month old LO always fall asleep during feeding? I try to tickle him, put down on the bed and carry him again but still unable to wake him up. I’m so worried will he hungry as he only drink half of his milk. Sometime even I’m able to wake him up he will still fall asleep after few sucks. And how do I burp him if he fall asleep?