My LO always overslept

Shud i wake my LO to drink his milk? He always sleep 6 - 8hrs skip his feeding time. My LO only 3M. He usually sleep from 8pm+/9pm+ till nxt morning 6am.. i try to feed him more aft he skip his feeding but he jus drink usual volume. Infact he drink lesser n lesser.... from 8 feedings (90ml) to 5 feedings (120ml) a day.. abit worrying..