Robin Williams insisted on drinking real alcohol while filming a restaurant lunch scene on the set of "The Crazy Ones" last year...and the cast said the liquor actually calmed him down acceding to the New York Post's Page Six.

Cast members described him as disliking the chemistry on the set...and bemoaning the fact that he had to work in television to pay alimony to his two ex-wives.

A source told the news entertainment Radar Online that he "was sleeping almost around the clock during his final days," and he wasn't eating much, plus he would often complain that "he was just so tired."