This sounds so tough. Difficulties that impinge on sleep can have a special kind of agony to them. I'm really sorry you're going through it. I think there's a lot to think about in your post.
On the level of simple "sleep hygiene', it sounds like you and your DD are already doing many of the 'right' things - plenty of outdoor activity/exercise, good diet, attempting a regular bedtime routine, stopping screens early, etc - and it can be important to keep these things going consistently. As you might know, there's also evidence for consistent getting-up times (trying not to allow lie-ins at weekends, etc), getting plenty of natural daylight (and ideally a bit of exercise) as soon as possible after your DD gets up, even on non-school days. Y
ou're obviously already thinking broadly about what might be going on and including any possible physical issues in this, and I think you're right to at least consider these in the mix, so (if you haven't already), it might be worth a check with your GP for basic possible physical issues. (By the way, when you talk about the breathing noises, I'm assuming you mean when she's awake - so not sleep apnoea or anything like that - and that you've checked out that this is a tic/habitual, rather than physiological? It sounds like this is the case, but just wanted to check).
Also, have you heard of 'bedtime fading'? You'd start by getting your DD to go to bed only at the time she normally actually falls asleep (sounds like this would be about midnight?), with a calm routine beforehand (and consistent getting-up time next day). Then you gradually move this earlier (e.g., by 10/15 minutes a night). I know this sounds (and, short term, can be) difficult for both of you, but there's evidence that it can also be very effective. Since she's 12, I'm guessing that sitting down and talking this all through with your DD - at a time which isn't bedtime, and ideally when you're both relatively relaxed - could be important.
There's lots to read online, but some websites/leaflets it might be worth checking out: www.rcpsych.ac.uk/mental-health/parents-and-young-people/information-for-parents-and-carers/sleep-problems-for-parents www.acorneducationandcare.co.uk/wp-content/uploads/sites/4/2022/05/Issue-10-Sleep-difficulties-in-children-and-adolescents.pdf
But going beyond the sleep hygiene/sleep intervention things, there are other factors to consider here (and some of them might affect how easy it is to implement the sleep tips consistently). First, it also sounds like this all started quite soon after your DD's beloved grandmother died. It's quite common for children to struggle to sleep in the wake of grief, and sometimes there can be fears about sleep because children (and adults) can associate it with death. A loss like this can also make children afraid about being "left/abandoned" by other people they love, too.
I imagine you may already know about places like Winston's Wish, which can help children with their grief. www.winstonswish.org/ And of course, twelve is also
an age when your DD might be going through puberty, and hormonal factors can contribute both to anxiety and to changes in sleep patterns.
Second, it sounds like your and your DD's interactions can sometimes be quite difficult at the moment (something I think most of us go through at different times in parenthood). I wonder how it's making you feel, when your DD says the things you mention (about you being a bad mum, abandoning her, etc)? These can't be easy things to hear (perhaps especially when you're already dealing with having to go back to work full time - on limited sleep) and you might be experiencing some difficult emotions (anxiety? guilt? irritation/anger?) when she says them? It's also possible that at the moment, as well as saying these things in an effort to express some distress she doesn't know what to do with, your DD has found that saying them might serve the function of helping cement/protect times at night when you're exclusively with her (whether or not she's aware of this?)?
It can be particularly difficult to put boundaries in with your children when you're feeling guilty and uncertain about things. With this in mind, I wonder whether it might help to try to put some cast-iron times in, away from bedtime/sleep (and not dependent on any distress or sleep problems your DD has) when you can do something together that you both enjoy and she can be the sole focus of your attention. It could be almost anything - a half hour walk on a Saturday, cooking breakfast together, watching a comedy straight after you get in from work…? I know as I type this that it's so much easier said than done, and that as well as full time work you've got at least one other child to consider.
I also know it's likely to require buy-in from others (including her dad? Other family? Friends?). The reason for the suggestion, though, is that allowing your DD to have protected time with you - that has nothing to do with bedtime - could (as well as giving her time to speak with you about anything that might be going on) help you to have the confidence to start putting in any boundaries around bedtimes that you decide to put in. Knowing that you've had time together could help you assess realistically the accusations you're hearing, and to avoid basing your decisions on any hurt feelings or misplaced guilt.
And now to you, because it's not just your daughter who's suffering. This is so important. It sounds to me like you've been dealing with a huge amount: a recent family bereavement will have affected you and the rest of the family too, and your going back to work full time (on limited sleep) on top of all the usual demands of life will have had an impact on all of you. You sound like a kind, thoughtful, dedicated parent, and that comes with its own challenges. There are no easy fixes for this, I know.
When we've spoken with parents of children who are struggling, a few themes have come out. Try to notice without judgment your own responses to what's going on (if you're feeling exhausted, worried, sad, angry - anything - that's just what you're feeling right now). Don't expect too much of yourself - sometimes just surviving the day is all we can hope for. Try to make time to do things (whatever they might be - exercise, seeing friends, feeding the birds, watching YOUR choice of telly), to make you feel like you.
To sum up, here's my best guess from what you've said: 1) It's worth continuing to look at the sleep hygiene/sleep intervention side of this, and/but 2) it might be difficult to put any required boundaries in place without considering some of the other things which might be going on, both for you and for your DD. I'm not going to pretend there will be a "one size fits all" answer to this, and of course it's not possible to know what's going on from just one brief post. If things continue like this, it might be worth asking for a referral to psychological services to get to the bottom of it. But you asked "Should I just pander to her night time needs?" and I think that if by that you mean allowing your DD to dictate entirely what happens, even if it means you both losing out on sleep, then the longer-term answer is "no". There's plenty to try. I hope things get better soon for you both.
post edited by MNHQ at poster's request.