I really didn't want to link to this article because unfortunately it says it appeared in Penthouse, the sexist,woman-hating,degrading and violent pornographic magazine in 1984,but I can't find the full interview anywhere else.
This is a great interview with John Lennon and Yoko Ono at The St.Regis Hotel in September 1971. And Yoko was asked if she knew about what really went on during The Beatles tours,and she says she had thought that he's an artist I'm sure he has had a few affairs, and she said she was really shocked and she said Oh God! when John told her the whole story about what he called all of the raving that went on their tours,Yoko said she had never heard the word groupie before.And Yoko was no innocent either,John was her third husband,she had a daughter with her second husband,and she had quite a few affairs and even abortions in the 1960's.
John is also asked if playing 8 hours a night from 1960-1962 as The Beatles did in Hamburg Germany improved their playing and he said oh amazingly because before that they had only played bits and pieces but in hamburg they played for hours and hours and hours together and that's how they developed their rock n roll sound and playing.He also mentions how they took (meaning speed pills) to stay awake playing so long.