Subliminal messaging and suggestion is real and I say this as a scientist, a hypnotist and a hypnotherapist myself.
Suggestions won't make your hair grow sadly but it's completely normal and expected that your head would tingle when you were told to focus on it and expected to feel 'something' working.
Hypnosis is a powerful tool, I specialise in treating patients with gut disorders (that have a neurological component) and the processes and results are backed by good quality peer-reviewed studies.
I won't go into the details of subliminals here as it's a long and complicated subject, and the extent and degree to which it works depends largely on the implementation. Some of the techniques are pseudoscience such as briefly flashing messages on a screen, but others involving techniques such as dichotic audio and musical cues can be very effective when combined with traditional hypnosis suggestions.
