We knew Matt Smith might have a tough time of it when he took over as the newest Time Lord, but until now we didn't fully realize what he was in for. According to papers published in the BBC Archive, a Doctor's transformation is meant to be a "horrifying experience," reported the BBC.
Per a 1966 internal memo, when the first Doctor, William Hartnell, regenerated as Patrick Troughton, the transformation was meant to convey the "hell and dank horror" of a bad LSD trip.
"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. "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."
Even the new Doctor's appearance was meant to reflect his unnerving change: "His hair is wild and his clothes look rather worse for wear (this is a legacy from the metaphysical change which took place in the Tardis)."
Let's hope things don't get quite that bad for Matt Smith. But if he debuts with a case of the munchies, at least now we'll understand why.