Violent sleeper! Is this normal?? (X-posted in nighttime parenting)

[Cascadian]

I coslept with my kids until they were 3 and 5, and since moved them out to their own shared room. Until only recently (like a month), either DH or I would lie down with them in their joined twin beds until they fell sleep (they're now 4 and 6).

DH is out of town, so I gathered up the kiddos and put them in our king bed for a week - a fun slumber party for all us gals, right?

O.M.G. My 6 year old has suddenly turned (suddenly? I don't know - we haven't slept through the night together in a year) into a violent sleeper! She flails, kicks, moans, talks...last night (in sleep mode) she was weeping. Two nights ago, she was kicking her sister *hard*, and sat up (still asleep) and whacked her twice on the back (presumably for space, except that she was crowding her sister's side). I was horrified! I don't know if this is normal for her, or if it had to do with have some long, overstimulating days at school/extra-curric activities, or the spooky Scooby Doo movies they rented...

I had horrible sleeps this week due to waking up from her movement/need to be comforted. FWIW when they sleep together with their twin beds combined, there's a 'gap' in between where the beds join, which they rarely cross over so there's no safety issue with her sister. I noticed the violence towards her sister when I was sitting on the edge of the bed watching a DVD on a handheld.

Is this a normal age-related thing? Wierd? Gah!

[Mamato3wild ponnie]

My 5yo sleeps on a twin mattress on our floor wedged between our king and the wall and he will kick and kick our bed at night, sit up, talk, grind his teeth, all while still asleep! Some nights i rub his legs while he's kicking....im not sure what it is about all the movement and kicking...i thought maybe his legs were cramping up or his muscles were spazing....I'd love to hear if other mama's noticed the same thing as we do!
He coslept with us up till about 2 months ago...and he did this in our bed also.