I know this might not be what you want to hear - I know it wasn't when my daughter was that age....around 4 months they become so distractable and excited about the world around them, sometimes they regress. Nighttime feedings can become very important to their overall calorie intake because often they don't nurse as well during the day ( mine doesn't!!). Some babies just wake at night and will grow out of it eventually. I know it can be hard to hear but if he's waking, it's because he needs something from you, whether that something is a feeding, a dry diaper or just a cuddle or some comfort nursing. It's hard, I won't pretend it's not, my daughter is 8 months and wakes at least twice a night still. You can try some of those approaches I guess, but to me most of them seem very harsh -- babies don't generally have the capacity to manipulate us by crying, its' their only way of communicating their needs. I hope he starts to sleep better for you soon.