Let me just quote Timothy Leary here (Playboy, 1966)
The sexual impact is, of course, the open but private secret about LSD which none of us has talked about in the last few years. . . .
Sexual ecstasy is the basic reason for the current LSD boom. When Dr. Goddard, the head of the Food and Drug Administration, announced in a Senate hearing that ten percent of our college students are taking LSD, did you ever wonder why? Sure, they're discovering God and meaning; sure, they're discovering themselves; but did you really think that sex wasn't the fundamental reason for this surging, youthful social boom? You can no more do research on LSD and leave out sexual ecstasy than you can do microscopic research on tissue and leave out cells. . . .