Sullen and stroppy 7yr old DD - at my wits' end!

[SheDancesTheFlamingo]

DD is 7.5 and showing behaviour that I would associate more with a stroppy teenager.
She's almost constantly moody or grumpy and can instantly change from happy to tearful. If there's not constant stimulation then she goes into a sulk. (example - she came back from the swimming pool with a friend which she enjoyed thoroughly and then went into an immediate tearful huff because I was not armed immediately with another exciting activity).
Also, she's become very disobedient, and appears to be purposely goading me with refusals to do what I ask to the point that I lose my temper.
I've tried to ask her why she behaves like this and find out if anything's bothering her but she doesn't appear to have any issues. Her teacher (and our childminder while I'm at work until one hour after she finishes school) both say she's delightful and exemplary in behaviour so this "attitude" seems to be reserved for my benefit.
I try and fill her week with fun activities but nothing seems enough.
My only thoughts are that maybe she's not sleeping enough- we put her to bed at a reasonable time but she insists on sitting up and reading for hours. Not sure how to police this without removing all books and toys from her bedroom. It's also getting very hot where we live (in Cyprus) and I wonder if she's getting disturbed sleep.
Quite often she wakes in the night, too, claiming to have nightmares. As you can imagine, these disturbed nights have a knock-on effect on me too, so don't help with our ability to tolerate on another!
Does anyone empathise or have any advice, or can tell me it's just a "phase" and she'll grow out of it?

[TheProvincialLady]

Maybe she is just too busy and over stimulated and can't relax?

[SheDancesTheFlamingo]

TPL - I did wonder that, but when I suggest that we do sonething relaxing, or just "chill out" she goes into a strop because she's 'bored'.
I try and allocate at least an hour's wind-down time before bed, too, but it's not working so far.
Thanks for replying, though

[karise]

I could have written this post myself- except our DD is nearly 7!
I don't have any answers, but I just thought you might appreciate that you are not on your own!
There is no chance that DD does too many activities at the moment though, so I wouldn't expect that to be the problem.
Might she be bored at school? This is something I have long suspected of our DD...

[WolframAlpha]

This all sounds very familiar, sometimes I think it is the effort of being 'good' in all these different situations, that you are a safe person to unleash all this stuff on. Also, tiredness definitely has a big impact, maybe earlier to bed and put the reading on a timer?

Mine is older now and a lot lot better - I wonder if there is a hormonal surge or something at this age?

[SheDancesTheFlamingo]

thanks for everyone's support.
things aren't looking good for tomorrow. It's ten o'clock here local time and I've just spent the last three and a half hours trying to calm down a hysterically tired DD enough so she can sleep.
I wondered if she's unwell but there's no obvious symptoms.
will keep you posted, thanks again xx

[3littlefrogs]

A good way to encourage early nights at this age is to do a quiet activity together - even a bit of pampering - foot spa, foot and leg massage, toenail painting - it is relaxing and allows winding down.

Nightmares can be due to overtiredness/overstimulation or anxiety/stress.

Maybe the books are overstimulating and some soothing music - like the stuff played in health spas - might be better.

Could also be attention seeking. Do you have plenty of cosy/quiet time together?