Hypnosis, if used improperly, can pose dangers in that you are opening yourself up to the suggestions of others while you are unconscious. If the hypnotist makes suggestions that are detrimental to your spiritual life, then you could run into some problems.
For example, a hypnotist might subscribe to New Age or occult philosophies that run counter to Catholic doctrine.
One of the big pushes for the New Age and occult philosophies is leading people to think that they can be empowered on their own without the help of the Creator. Creating a “Superman” of yourself if you will.
“Will to Power” is the phrase you sometimes hear in these circles. It’s basically about creating your own successful outcomes through visualization, your “positive” mental outlook on life, and “thought control”.
As Catholics, however, we have only recourse to God for our empowerment. We are not gods ourselves, but live only through the grace of God. Anything we have, comes from God, whether it’s family, prosperity, health, etc.
Prayer, and a steady diet of good Bible reading, attending Mass and the sacraments, would give better results than hypnosis.