Patrick Dempsey has noticed the "lighter" atmosphere on the set of medical drama GREY'S ANATOMY since the departure of controversial castmate Isaiah Washington. Washington was written out of the show earlier this year (07), following a media storm last year (06) after he was alleged to have made homophobic comments about gay co-star T.R. Knight, which prompted an on-set argument with Dempsey. The cast have only just returned to the set to film Season 4. Dempsey says, "It's a lot lighter, people are having more fun. "The energy and the adjustments make a big difference."