Nighttime feedings

I'm wondering if any of you all are still schedule feeding at night or are most of you letting your baby wake you? Little man is 6 weeks old. Until 2 and a half weeks, he was under birthweight and at that appointment the ped mentioned not letting him go more than 4 hours without feeding, so we've been setting an alarm. There are nights, like tonight where he doesn't seem to want to get up. If it's unnecessary to keep waking him, I'd rather let both of us sleep. We don't have another appointment for 2 more weeks, but I do know he is above what they expected him to be at his last weigh in. Basically, I'm wondering if it's okay to go ahead and let him wake us at night to eat.