Internal memos recently posted to the BBC Archive reveal that Doctor Who's "regenerations," in which the Time Lord was replaced by a new actor, were meant to convey the experience of a bad acid trip. From a 1966 memo about the tansition from the first Dr. Who, played by William Hartnell, would be regenerated into the actor Patrick Troughton:
"The metaphysical change... is a horrifying experience - an experience in which he relives some of the most unendurable moments of his long life, including the galactic war," it said."Doctor Who regeneration was 'modelled on LSD trips'"
"It is as if he has had the LSD drug and instead of experiencing the kicks, he has the hell and dank horror which can be its effect," the memo added.