3yo Nightwaking. Help!

[WindyCityMom]

My 3yo has been nightwaking a LOT for quite awhile and it is getting frustrating and old and I can't handle it anymore.  She sleeps in a toddler bed next to ours.  We cosleep with my 12mo.  She goes to bed around 8-9pm which is a good time for her.  She then wakes up around midnight each night, and ends up staying up for a few HOURS.  It's incredibly hard for any of us to get sleep.  Her waking is consistent and has nothing to do with noise level in the room or anything.  Our house is an open floor plan so our bedroom is our living room, playroom, and kitchen, essentially, but we're quiet.  If we're up at that time, I'm usually on MDC, knitting, reading, or doing another quiet activity, DH is on his computer in his room reading or watching videos with headphones on, and the baby is usually sleeping or nursing.  Nothing to wake 3yoDD up.

She has CONSTANT extreme hunger and gets something hearty before bed so as to keep her full longer.  She usually requests cheese when she wakes up or at some point during her awake time at night (I deny her the cheese, and tell her that eating is for morning and she's usually OK with that).  The cat doesn't bug her.  She sleeps with her lovey, her doll, and another plush doll.  She gets a candle and a story before bedtime.  Always a bedtime routine.  She wakes up, yawns, tosses and turns, talks to her doll, etc.  She also does this horrible chewing thing that sounds like someone chewing with their mouth open, which is my pet peeve and a not so nice noise to hear while breastfeeding my nursling in bed (gives me that icky creepy crawly throw myself off a balcony feeling).  She'll sit there picking her toenails and generally just whining sporaddically for no apparent reason.

She doesn't nap unless she's extra tired out from an activity or she was overwhelmed or something... which isn't often.  She eats zero hfcs, artificial colors, and has very few refined sugars and doesn't have a high sugar intake period.  When she does have extra sugar (refined or otherwise) it doesnt correlate with the nightwaking either.  This is all the time.

She was never breastfed (uneducated 17yo me...) and STTN by herself from 6 weeks on.  She has always been an excellent sleeper.  I don't get it.

Could her bed be too uncomfy?  It's a toddler bed with standard crib mattress.  Not very cushy at all.

Anyone?  I'm at a loss!  When she wakes up, we all wake up.  And I need my sleep as I'm still nursing my 12mo through the night.

[bodhitree]

To be honest, I'd try just feeding her as soon as she wakes up to see if that helps her get back to sleep faster. She might just be waking because she is hungry, and at that age I wouldn't expect her to be able to convince herself she isn't hungry so she can go back to sleep. I have trouble doing that myself sometimes.

[WindyCityMom]

Thanks :) I have found that she doesn't go back to sleep even if I do give her a quick snack right away.  She doesn't always request food, and when she does it's not right away either.  It seems like an idea that she gets out of boredom from just laying there.