Sometimes I wake up at night and cannot fall asleep because of delusional thoughts, words in my head, the brain begins to actively sort out this delirium, what is happening to me?

Don't worry, this is a common occurrence among people who are very concerned about life. You are looking for an answer, but do not find it right away, hence the thought-turn. Tell yourself, now is not the time to look for the answer, you need to sleep, the morning is wiser than the evening. That is, you need to distract yourself from thoughts. This is how I do it. First, I relax the muscles of the face. Make a half smile, the muscles will immediately relax. Then the shoulders, chest, abdomen, pelvis, hips, legs, and feet were relaxed from top to bottom. And then look around the body where you feel the pulse, focus on your stomach, caught it, look elsewhere, in the thumbs, start with the right, in the same place in each finger, did not fall asleep, go to your left hand. You will practice for a couple of nights, then you will be cut off on the first pulse you catch. While searching for a pulse, all your thoughts disappear. Tested on myself dozens of times. Go ahead and find it. Good luck.

Nothing special happens to you, this is the usual intellectual overstrain caused by work or study. You just have to try not to think about anything and relax. This book provides effective techniques to gradually eliminate these problems.

Very relevant.