Sleep anxiety.

Hello

I'm just wondering if anybody has any advice or has gone through similar with their children..

So my 10 year old daughter has recently started to have sleep anxiety. This has been happening for years actually but she got better until a few months ago. She refuses to sleep, she cries and is so scared to go to sleep as she thinks she will die in her sleep and she also has such a massive fear of me or her nanna dying. I honestly just want to help her but nothing seems to be working at the minute and I don't know what else to do to help calm her.