Not to stop my son coming over when grandson is in bed.

She has no sleeping difficulties. She's a night worker

Bring a natural " night owl" doesn't mean people has sleeping difficulties

And as for " not knowing what she'd be like". Well she's perfectly normal woman woman. None of all these conditions that everyone seems to have nowadays

A sample size of 1 isn't particularly sound, especially as you have no way of knowing what your daughter may have been like if she had got the recommended 14h sleep.

If she's experiencing significant difficulties sleeping at night into her mid 30's ("still bloody nocturnal"), that could well be part of the impact

If he’s shouting so loud it’s waking a baby up who is upstairs and banging/lumping around to go to the toilet, I hardly think he is tip toeing through the door. I would imagine it more akin to a policeman with a battering ram barging in.

I mean, it is. Tell him to keep it down!
Having a baby who is a difficult sleeper is stressful, combine that with whatever circumstance has led your daughter (and grandchild) into moving in with you lus dealing with a loud, inconsiderate brother must be awful. Hopefully they get their own place soon.

Look he is trying as you say he moderates his voice for a little while when reminded.

Can you try having a visual reminder that you show him as soon as he arrives and you keep neatby to point to when his voice starts to.get loud. Maybe a notice on the table or fridge that says has a visual of someone being quiet or making a shhh sound, with the words " quiet voice so baby can sleep" or something like that

It is less tiring and more consistent than reminding him vocally. Eventually he may remember in his own or at least you will have to remind him less often to keep his voice down

Better read it later when it gets late then hadn't I?

Still hasn't caused my DD issues. In fact she's still bloody nocturnal

The link will lead to this study on poor quality sleep and the effects in infancy

https://www.sciencedirect.com/science/article/pii/S1389945724000595

here is some late night reading for you.

Couldn't agree more with this. It honestly just feels to me that you don't want your daughter or grandson living with you and rather than being direct your just making it horrible for them. I actually find it really sad that you have said she's had a change in circumstances (obviously a relationship breakdown) and rather than support her your like going on about making your son feel welcome and comfortable because he has autism? It's like you are trying so hard to make your son feel secure your over looking your daughter's needs.

Its very possible that DS has been given the message that "he cant help it" all his life and this is a big part of why he does not see he should make an effort here. Autism does not make you an arse, but being spoiled and favoured does.

Clearly the son is jealous that all the attention isn’t on him for once so he’s deliberately trying to make things difficult for his sister.

Op won’t be back

Id ask him to continue visiting but to please be a little quieter. I’d also get a white noise machine for the baby, they’re fab at drowning out noise

Really? How do you get that? My eldest never slept before 10 or 11pm as a baby, would wake up in the night until she was past 3.5 ( I know this as DD 2 slept through the night first) And be awake by 7ish . Started nursery 8.30. It wasn't silent where they had naps in nursery either

She's in her mid 30s and absolutely nothing wrong with her health or development and never had Been

Toddler having tantrums and screaming is ear splitting

But why would you not make those adaptation if you knew it made life better for your loved ones.

The extra effort in calling vs ringing the bell is negligible.

Not stamping your feet on the way to the toilet isn't difficult

It's seconds of very slight effort to save her daughter hours of work and her grandchild days of feeling tired.

I have learnt over the years that people are either door closers or door slammers. My family are door closers but we often have guests who just slam doors behind them, without depressing the handle & latch. It shakes the entire house.

If said young man is closing the front door by slamming it behind him then YABU.

If he’s capable of holding down a job then he’s capable of learning to speak at a normal volume to help his sister’s baby (and his nephew) to fall asleep. None of you seem to be particularly bothered about the baby, just your son’s feelings.

Some babies are temperamentally very light sleepers and there’s sweet FA you can really do about it no matter how many white noise machines you invest in. If we all slept exactly the same way then no one would be an insomniac, nor would we have night owls and early birds.

how is she trying when her answer is he can’t come round on a weekday.

How is it not like being a hostage or prisoner in your own home if you even have to creep to your own bathroom and using your own front door can wake the baby. It means all visitors or even trips out the house or bathroom are restricted. Because ops on edge about waking this baby who can’t sleep in a normal home.

Said forget the brother this is just stuff ops having to do.

God help her if she ever has more children 🤣

There’s a very bit difference between normal household noises and someone literally shouting so loud they can be heard upstairs and banging around in the bathroom. Imagine yourself asleep right now and someone literally comes into your room and screams in your ear, would you like that, being startled awake multiple times a week? That’s effectively what he is doing to this poor little baby. The son is being purposefully spiteful.

Hostage ha right! You’re filling in gaps with nonsense

and it does sound like she is trying to sort out the sleep, it can’t be easy though being in a new home for them The white noise machines are awful

Daughter needs to sort the sleeping, white noise, co sleeping or whatever.

She shouldn’t expect to hold her mother hostage to silence because she needed to move back in. She moved back into her mums house mum didn’t move into her home.

Op doesn’t have to give up her evenings because of it.

The baby is not sleeping though. When he’s there. Unfortunately for him and Mum

If the baby slept for half an hour, then was woken, that could act much like a danger nap, amd the baby might not be able to sleep again for 4/5 hours. Therefore instead of sleeping 8-8 and getting 12h sleep, it would be up u till 1am, and only get 7h. If that's happening multiple times a week, it will be impacting the babies health and development.
It will also be awful for the mother to have to deal with the overtired baby, both that night and the next day, then just when she's got it back to a normal sleep cycle, the brother visits again and does the exact same thing.

Even granny has to creep though this isn’t even really about the son. The whole house has to move and be silent once the baby sleeps basically.

toddlers voice Vs grown man’s deep voice and stomping feet, hmmm not the same

What a stupid comment. Babies thrive on routine. A one off late night because of a wedding or special occasion, absolutely. But regular weekly interference, no. If the baby needs to be in bed by 7, then that’s the time he goes. How can you even suggest that a 1 year old should be making accommodations for a grown adult so he can shout the house down and crash about at 8pm.