Scared Meditation at Night

I’ve been meditating consistently for about a year and recently had a really intense experience while lying down at night. Typically I just meditate in the morning sitting up but today I was propped up in bed, doing triangle breathing. After about 20–25 minutes of listening to theta binaural beats and focusing on my third eye, I suddenly felt a strong sense that something was watching me, which made me scared because it felt so real. I started seeing a dark purple, dome-like visual, almost like I was looking up at a night sky. At the same time, my body felt extremely light, almost like it disappeared. My heart started pounding, and I had a strong urge to open my eyes because it felt like something was right there. I also felt a slight wiggling or movement in my bed. I tried to stay calm and focus on my breath, but the fear didn’t go away, so I ended the session early and felt pretty shaken afterward. Has anyone experienced something like this during meditation? What’s actually happening in this kind of state?