Sleep is very challenging for me and I go through times where I switch into trauma parts and experience flashbacks as soon as I get into bed. That hasn't been happening recently but instead I have been experiencing nightmares around the trauma. But I think I have had times in the past where parts have been able to "meet" and interact with each other in sleep and dreams too.
Have you tried asking inside if anyone knows what is happening or why it is? Maybe someone has some insight into it all.
Sometimes I try to do a meditation as I fall asleep when things are bad. Sometimes that helps and sometimes it doesn't.
I hope you are able to figure out what is going on and things settle down for you soon.