The actor, famous for his villainous role in Coronation Street as well as parts in Casualty, Taggart and more recently the critically acclaimed The Loch, posted on Twitter this morning that he spent most of Christmas Day sleeping.
Gray was diagnosed with tonsil cancer last year after seeing a doctor about swollen glands in his neck.
The 51-year-old posted on social media: "Happy New Year. I hope you all had a wonderful Christmas. Unfortunately I have taken a slight dip in recovery. The pain has increased and I spent most of Christmas asleep.
"Did manage a couple of games of Jenga and Yazi so all was not lost.
"I am thinking of everyone going through cancer. It is a long slog and mentally takes its toll. I wish you all the best and thank everyone for the support they have given me. As always stay strong."