Sir Paul McCartney has spoken about the copious amount of drugs The Beatles consumed in their career and expressed dismay at how they managed to survive the period.

In an exclusive interview with Entertainment Tonight, he said, 'We were overdoing substances and really getting crazy, as we all were.

"We'd be falling asleep, the kinda thing when you can hardly get your head off the pillow. You go, 'Woah, I'd better get my head off this pillow.'

However some experiences on drugs led to writing The Beatles classic 'Let It Be'.

McCartney said, "I had a dream, where my mother, who had been dead, by then, 10 years came to me in the dream and was very sort of helpful and very calming, and it was lovely just to see her... and she said, 'Don't worry about it... Let it be.'

'I went, 'OK', and I felt so good... and I woke up and wrote Let It Be. I thought, 'That's a good idea for a song.'

(by David Renshaw)