NBC's "The Tonight Show Starring Jimmy Fallon" is undergoing changes since head writer A.D. Miles will reportedly be leaving the show. A.D. Miles has been working for the show back in 2009.

Hollywood Reporter revealed that the 45-year-old will leave the late night show as he is planning to go back to acting and narrative writing which was said to be "mainly for films and half-hour series." According to sources, A.D. Miles will be transitioning in the next upcoming weeks. Further, sources revealed that Miles have thought of exiting for some time as the show's format has become "very demanding" which hindered him in pursuing his other interests. With A.D. Miles leaving the show, it was reported that he and Jimmy Fallon will still work together in an upcoming animated feature.

Before his stint on Jimmy Fallon's show, according to Variety, he was said to have portrayed comedic roles such as Gary in "Wet Hot American Summer" and wrote for Comedy Central series "Dog Bites Man." The show's veteran writer is also said to go back to Los Angeles with his family from New York where the "Tonight Show" is based.

A.D. Miles in a statement, as cited in the report, said that working with Jimmy Fallon for eight years gave him "all the confidence" to be out on his own and instead, work on a movie with Jimmy. The "Tonight Show" host, on the other hand, also lauded Miles for being there since the launching of "Late Night" and that he cannot wait to be working again with him soon. "He's family to us, and we are gonna miss him," Jimmy Fallon said.

Moreover, A. D. Miles decision to leave the show was said to have an effect on the show since it has been competing on ratings with CBS' "The Late Show With Stephen Colbert." The CBS show had reportedly garnered more views since the presidency of Donald Trump because of Colbert's "politically-themed comedy." As of this writing the "Tonight Show" has yet to name a replacement for its head writer.