Why what worked for the first baby isn't working for the second
If you had your first baby and somehow figured out the sleep thing, and now your second baby has arrived and absolutely none of what you did the first time is working, you are not losing your touch and you are not imagining it. The thing that's happening is that you've got a different baby. That sounds glib but it's the actual answer.
The first time round you probably learnt a set of moves that worked for the kid in front of you. Maybe a particular wind-down. Maybe a specific timing. Maybe a method or an approach you settled on after a few weeks of trial and error. By the time your first was a year old you had a small, honest sense of "here's what works at our house," and you carried that into the second pregnancy assuming, reasonably, that it would carry over.
It mostly doesn't. And the reason is something that's hard to talk about properly because it gets dismissed quickly when people say it.
Temperament is not parenting
Babies arrive with their own nervous systems. Some are quick to settle, some are slow. Some startle easily, some don't. Some can drop into sleep on their own from very early, and some need a lot more support to get there for a long time. None of that is parenting. It's biology you didn't pick.
When the first kid was the fast-to-settle kind, you probably absorbed a lot of credit for it without noticing. The second kid arrives wired differently and the same approach falls over. The honest read is, your skill didn't change. The kid did.
This is the bit that's hard to sit with, because if you accept that the first time was partly the kid, then you also accept that you can't out-strategy your way through the second time. You can support the second kid better and you can adjust around their wiring. You cannot make them be the first kid.
The comparison trap
The cruellest thing happens at the comparison moment. Other parents will ask how the second is sleeping and there's an unspoken expectation that, having done it once, you've got it. When you don't, it lands as failure rather than as the next totally normal experience of meeting a different child.
The way out of that trap, in my experience, is to stop comparing the second kid's sleep to the first kid's sleep, and start comparing them only to themselves a fortnight ago. Are they shifting? Are the wakes getting shorter, or further apart, or are bedtimes settling in? That's the only honest read.
What to actually do…three small shifts
I usually find these three shifts help families coming through this for the second time.
One. Strip the strategy back to the bones. Whatever set of moves you carried over from the first kid, treat it as a hypothesis, not a plan. Pick the two moves that feel most like load-bearing walls (often a feed-related rhythm and a wind-down) and let the rest go for now. The second kid needs a structure built around them, not the structure that worked for someone else.
Two. Watch them, not the clock. Wake windows and timing rules are useful as a rough frame but they were built on averages of which your second kid is one data point. If the windows say one thing and your kid's nervous system is saying another, listen to the kid. The clock was always meant to support the read, not replace it.
Three. Plan for the partner moment. With one kid you could often roll with whoever was free. With two, the cognitive load doubles in a way that isn't proportional. Decide who has which kid at which moment, and write it down somewhere visible. The mental load of "who is doing what tonight" eats more energy than most people give it credit for.
None of this is a method and that's deliberate. The first time a method may have worked partly because it landed on a kid who was going to get there anyway. The second time you're working with a child whose biology isn't doing you any favours, and the kindest thing you can do for both of you is to stop assuming you should already know.
What's the thing your second kid is doing differently, that's been the hardest to get your head around?