Is it possible to learn other languages from doing past-life regression, meditating, etc..
Polsan
Perhaps. I have learned a foreign language (Russian) in my sleep when I was in high school.
The special linguistic program required that we learned @3 pages of a book everyday by heart. I hated learning anything by heart. Every time I asked a friend to read the text over the phone so I could record it on tape. I was too lazy to even read it myself.
After recording, I removed the recorded piece of tape from the reel, glued ends together and played this "endless" tape via small headphone very quietly when I was asleep. Typically, the tape, which was hung around my bedroom on nails, broke up after an hour or two and I could never be bothered to fix it.
I found that the next day all I needed was to read the text ONCE (it took me 5-10 minutes) to pass the everyday "test". The method turned out quite a success for me. At the end of a year I REALLY could recite the entire book, not remembering any effort. I was among those who could remember most. 35 years later Russians are still amazed how well I use idiomatic expressions.
Back to your question. If I could accelerate my learning so much using my sleep, I suspect that there is a great potential in learning via altered states of consciousness. Even if we only use a small part of our natural sleep.
There may be some dangers though. Dangers are related to cluttering your mind with misinformation and false data. Watch what you learn.
Tom