Also, there's a form of meditation that is known to work.... I spontaneously figured this out on my own once when I felt "uh-oh... feeling scared... bad trip approaching", then read an an entire web page about it somewhere that I have now lost.
A type of meditation where you "step back a level" from the experiences that are scary or depressing... and try to BE the "eye" that is one level up, watching the normal "you" going through the bad thoughts. If the bad trip invades this level, step up again, and be the EYE who is observing THAT viewer.
Its hard to explain but somehow its very easy to do when in a bad trip, almost intuitive.
Like playing "Watch the Watcher".... I get a sensation of mentally BACKING UP, and the fear in me subsides and I start to have this really detached cosmic point of view, as I become the cosmic mind's eye watching the "silly me" below get frightened by the scary monsters and hallucinations
You tell yourself that EVERYTHING IS ORIGINATING INSIDE YOUR OWN MIND... your OWN consciousness is the one who is creating ALL thoughts and feelings, including the scary, threatening ones you feel during a bad trip... then you back up a level and observe this very process down below in the "normal" you, generating its own chimeras to scare itself with.
This kind of mediation has a name but I forget what it is. In meditation it is used stop the thought-generating machine in our heads... you try not to think, but if/when you do you visualize stepping back and observing the level of mind that is concocting the "thought.".. and just by this simple shift of inner perspective, you are no longer "having" the thought, but rather now you are "observing it from afar," and it does not really belong to you or control you and you can let it evaporate.