I searched covid vaccine and rem sleep and a bunch of stuff popped up and most of it's biased but it is intriguing: https://www.tmc.edu/news/2020/08/the-strange-and-vivid-dreams-of-covid-19/

https://www.inverse.com/mind-body/intense-dreams-covid19-vaccination

https://pittsburgh.cbslocal.com/2021/03/22/crazy-dreams-covid-19-vaccine/

Edit: most people are blaming anxiety and stressful experience but I'm not having crazy dreams and I have huge amounts of anxiety so I don't think it's as simple as that.(also not vaxx'd) I hope your wife's dreams get better, I'd still try the magnessium for her.

I searched covid vaccine and rem sleep and a bunch of stuff popped up and most of it's biased but it is intriguing: https://www.tmc.edu/news/2020/08/the-strange-and-vivid-dreams-of-covid-19/

https://www.inverse.com/mind-body/intense-dreams-covid19-vaccination

https://pittsburgh.cbslocal.com/2021/03/22/crazy-dreams-covid-19-vaccine/