Ruminating? Overthinking? Insomnia?
People who have never tried hypnosis often have one very important question:
Will hypnosis work for me?
The short answer is: Hypnosis works for everyone. Everyone can be hypnotized.
The longer answer is: Some people are less open to being hypnotized. Often this is because they have strong "protectors"--rational, mathematical, logical parts of their personality that are always thinking, always doubting, always asking questions.
Protectors like these won't let down their guard easily. They need to be reassured, listened to, validated. Then, usually, they will step aside and allow a person to relax into hypnosis.
Does this description seem to fit you?