Sleep deprivation + sleep = you don't remember what sleep deprivation is any more. I would hesitate to even give advice when asked by a parent of a newborn, because you really have to be careful. I mean, you're dealing with someone who is emotionally fragile and terribly unstable and I say that with deep love.
I look back at myself in those days, and I couldn't tell friend from foe. Sometimes I wonder why anyone still talks to me these days.
But one thing that having three kids at the same time taught me is that I have less effect on my children's behavior than I might assume I had if I only had one at a time. Every kid is different even when they look a lot alike. Just because one kid likes to eat all the food, doesn't mean you will have success with another. So, I tend to keep my mouth shut because things that seemed to work on one, didn't work with all three. So I don't know what actually did the trick. They are all still alive, and I think that's worth something.
I also stay quiet because things are so blurry. Your brain eats those early memories. They're gradually removed from your consciousness and then they float away, replaced by new challenges that resemble nothing of your old challenges, but still seem to take up a lot of your frontal lobe. So asking me, a mom of three 4-year-olds, about newborns? I may flail around and try to be helpful, but chances are, unless I'm reading out of my bedside journal, I don't know what I'm talking about anymore.
That being said, in about a year or two from now, new parents who are now the proud owners of toddlers will be upset about entirely different things. Kids are inventive always looking for new and interesting ways of hurting themselves or others, or destroying something you love. They can't help it.
And that isn't to say it doesn't get better. It does it gets way better. You will sleep again. Your offspring will communicate with you with actual words instead of animalistic yelling and grunts. They will give you sloppy kisses and tell you they love you.
And you may end up forgiving the people who gave you advice.