Hi, My Daughter Aged 10 Has Recently, Since January, Started

Hi,
My daughter aged 10 has recently, since January, started to get regular nose bleeds. Last night she got one whilst asleep in bed. She eventually woke up, and woke me up, but by this stage the blood loss looked like a lot. She looked pale. My question...if she hadn't woken up would this have stopped by itself?? Should I get her seen by a GP? I probably will anyway. What would be the cause of this? I find it unusual that one can get a nose bleed whist sleeping. as in no physical activity prior. Thank you, Melissa