waking up while sleeping..

my gf has this thing where in the middle of the night, she will have to wake up, and walk around for a bit before going to bed again. It's not sleep walking.

She says that during the night, there is this feeling that wakes her up, and her body just feels all wierd and stuff, and it forces her to get up, and walk around the room for a while, before feeling better and going back to sleep.

does anyone know what i'm talking about? how can we fix this? is there a term for this?