I don't think it will do what you want, and could lessen your breastmilk supply. Instead, you could try a pre-nap snack (just don't feed to sleep) and cluster-feed in the evening to extend nights. As you start to move to a 4-hour EASY cycle (starting anytime now), lo will take more at each feeding, and hopefully sleep longer. Be careful to avoid overtired too - at 4 months, the world just got a whole lot more interesting! I know both of mine are very likely (have been since the start) to get wound up and not make it into that deeper stage of sleep, and sometimes it's hard to avoid.