disrupted rhythm

It's hard to say anything for sure, since you don't describe how your little boy behaves the rest of the time or if there's anything else going on (assuming that's known). I mean: my son and now my youngest daughter were/are very restless in their sleep, waking up quickly (from noises) etc. in their crib, and only slept well in the pram, Maxi-Cosi, or on my chest. But when I observed them, I got the impression that they really wanted to sleep, that they were tired. Both had/have reflux (which we eventually figured out ourselves by observing and ruling things out) and were/are very restless because of it.

We swaddled our son back then, and it gave him so much calm that he fell asleep nicely, despite still having symptoms.

We're now swaddling our youngest daughter for the 2nd day, and so far it's giving her a huge amount of calm.

So I'd say: observe your little boy and figure out why he's sleeping so poorly that way, then you can look for a solution.

By the way, I often hear that babies benefit from swaddling. You could certainly try that. Depending on how big/old your little boy is, you can swaddle him in 2 hydrophilic diapers or, if he's a bit older, with a top sheet. So you don't need to buy one of those expensive swaddling products!

Good luck!

How old is your little boy? Our youngest also had that phase in the first few weeks where he wouldn't sleep from 4 PM until midnight, and then slept straight through until 12 PM the next day (of course with feedings in between). We were advised to wake him up in the morning, keep him awake for a bit, and then put him back to bed so he'd get back into a day/night rhythm, which would make you both happier too So I'd definitely try waking your little boy up after two hours of sleep from 4 PM onwards, feed him, play with him, and then let him sleep again, so hopefully he'll save his long nap for the night. But... little babies have their own rhythm in the womb and now they have to adjust to what we find comfortable. This takes some time, and I'd definitely go through this period with a gentle touch, lots of patience, and love, because it will get better!!!