But yeah, as I mention in a reply to a sibling comment, she's tried therapy for years without much progress, though recently making some progress on that front.
Try these: https://www.loopearplugs.com/products/quiet
And at the same time have some calming barely perceptible background noise from a speaker somewhere in the room. White noise, brown noise, lofi, whatever works. Make sure the bedroom has blackout curtains and soft light.
As for cannabis, she doesn't have to smoke it. Appropriate edibles will knock her to sleep. Doesn't have to be a permanent thing either, breaking the cycle and getting good sleep for a few weeks is life changing and may be the start of a virtuous cycle instead.
I recommend both of you enjoy this video together: https://www.youtube.com/watch?v=mK2iXQm4LJs
Good luck!
My wife and my girlfriend are both jealous of the effect it has on me. But I’m jealous on the sleep-inducing or calming effect it has on them.
Please don’t assume marijuana affects everyone equally. It may work, but if it doesn’t, your girlfriend will know immediately so you can stop trying it. Ask her how marijuana normally affects her before trying that.
I leave it to you to research a bit further and perhaps try different kinds, with some trial and error you may get lucky yet.
Just saw they very recently approved some canabis oil drops for medicinal use here, so that might also be an option.
Your milage may vary of course