Help for dog having nightmares

[April2]

Hello, I'm not sure much can be done that I'm not already trying but here it goes; my toy poodle sleeps with me every night in my bed and almost every night it seems she's having nightmares that wake me up. She starts off whimpering and kinda snuffling and if I don't respond right away it gets louder and louder. I gently shake her awake, pet her and talk to her till she's awake and stops and then she's fine and quiet after that. This happens nearly every night at least once or twice in the night and now I'm tired every morning from waking up every night.
I'm honestly not sure why this happens as my other dog sleeps quietly all night, not a peep out of her till morning, but my poodle has these constant nightmares. Is there anything I can do that can help end this so we can all have a more restful night? Other than the nightmares she appears pretty healthy and plays and is active and eats well during the day. She's not being picked on by my other dog, either, they get along well. I just can't figure out why she keeps having nightmares at night.