Spiders swarming Through the bedroom Window

"Last night I had this really strange dream. In the dream, I was tidying up my bedroom, and I accidentally left the window open for a while, then shut it right away when I noticed, worried that some creepy crawlies might get inside. But it was too late. I noticed a huge swarm of bugs crawling in through a gap in the window frame. I first thought they were ants. But when I looked closer, it was spiders! So many of them. And worse, when I looked up, they were being followed by an enormous mother spider that was the size of a cat, with legs as thick as broomsticks. I was freaking out. I screamed for help. My older brother came in and cleaned up all the spiders, trapping the little ones in a jar to release in the garden and squashing the big one. And then I woke up terrified. It was 3 am and I found myself lying on my stomach. I usually sleep on my side. I have noticed I get nightmares when I sleep on my stomach. Not sure if that's a common experience."