5 month old waking up for 2hrs every night - please help!!!

[Mummyboo11]

For the past month my 5-month old daughter has been waking up every night around 3am for about 2hours. We have a 2-year old who is a very light sleeper, so when the little one starts fussing, I change her nappy (which is usually huge by then) and take her from her room and bring her to her cot next to our bed. Unless we leave her, she doesn't cry, is just super excited, fully awake, kicks and squeals until eventually she sleeps again. I have to hold the soother in her mouth for ages as she spits it out, but then fusses/cries when she doesn't have it. We play this game for about 2 hrs until she falls asleep. This has been going on for a month now and I am now beyond exhausted/desperate. I have tried tweaking various things but she still wakes up. She is bottle fed, has her last feed around 10:30pm and feeds again at 7:30am. Can anyone help please?!

Could be dc is hungry. Try introducing another night feed.

Could be drop in room temp. Mine all wake up if it gets too cold .

Could be bedtime too late is too early. Or that poor day sleep is causing it. What are naps like? It's useful to look at sleep over 24 hr period. 5 months they should be getting around 15 hrs on average. Could it be overtiredness that is causing it?

Thank you for your message mintbiscuit.
When this first started i was feeding her at 2:30am when she'd wake up and then she'd stay up for two hours as well! Also i don't think she's hungry as will not fuss for food in the morning, and sometimes will have less than what she usually has if i feed her before 7:30m.
Have got her heating up and a warm sleeping bag on, was nice and warm when she woke up last night.
Bedtime is around 6:30-7pm. Has 2 naps in the day, on good days (which are getting more consistent) one 40mins in morning and a 2hr nap at lunchtime.
Could it be the soother dependence? Also read about a 3-5 month sleep regression?

It doesn't sound like a typical sleep regression - that's usually multiple wakings rather than one long waking. It does sound like a bit of a habit but my DS had this sort of middle of the night party when he was having a developmental spurt - crawling, babbling etc.

I would get rid of the dummy. It is a great sleep prop but i she's waking for the dummy it is better to stop using it altogether.

I would also get a bigger nappy for nighttime sleep - just go up a size. Unless there's a poo I wouldn't be changing it at night.

The naps sound good - a third nap wouldn't go amiss but they can be a bit hard to come by when there's a nap transition. (from 3-2, 2-1 etc)

Why not put her to bed in the cot in your room? You can get to her quicker that way in the night and hopefully catch her before fully awake. Also by not having to lift her/pick her up, she has less reason to get excited or wake properly.

She is going through a developmental spurt, recently rolling and vocally being chatty. How long was your DS waking up when he had a growth spurt?
I do need to get rid of the dummy, you are right. Dreading that.

Honestly it was non stop for a couple of months as he crawled at 5.5 months, then got teeth at 6 months, then norovirus then pulling up to stand and then cruising at 7 months when he sttn until he got lots of teeth from 13-17 months.

They weren't all bad nights though. Eventually I'd just give him calpol and a cuddle and leave him to it as much as possible.