If he is only eating for five minutes and then going back to sleep then he truly wasn't hungry. I have a 3 month old who sleeps through the night. If he has made it all night before then you know he can do it. I wouldn't rush in when he stirs at night I would give him a few minutes to see if he settles himself back to sleep. I would get a sleep book. It talks about that in there and how to gently wean him off the night feedings. We use the book Good Night, Sleep Tight by Kim West. And yes the time is short that they are young but the longer you let him eat at night the harder it will be to wean him. And he isn't going to starve to death. If he is truly hungry he will let you know. But by now he should be going through the night. good luck.