Just like you I had a period of time where I was constantly afraid of losing touch with reality and going crazy. I was constantly looking for anything out of the ordinary and any suspicious sound or weirdness in my vision lead to a spiral of anxiety. What finally got me out of it (for the most part) was firstly realizing that this was actually a very common experience for those suffering from anxiety. And secondly, was to stop fighting and just give into the thoughts and anxiety. Any time I felt like I was about to crack I would just give in and literally say to my self "If I go crazy, then I do". In my experience fighting the thoughts never help, it only fuels the anxiety/fear.

Also I would suggest not giving much thought to anything you experience at night. My anxiety is personally the worst when I try to sleep because I'm left with only my thoughts and no outside distractions. The problem is at night you're already tired which can lead to strange thoughts and then there is Hypnagogia.