The actress, who found fame playing Raquel Watts on Coronation Street, said she had “two of the best roles she’s ever had” since turning 40.
She told the Sunday Mirror: “I’m 53 this year. It started at 49 with Tango in Halifax and then Happy Valley. I can’t complain at a time when most actors are disappearing. I seem to have become very visible.
“Age affects us all in the workplace. We all get a little less appealing as we get older, unfortunately.
“We should gather strength from the fact that the climate is looking very promising for women. But it’s very early days, and too soon to celebrate.”
Sarah won a BAFTA and a National Television Award this year for her role as Sergeant Catherine Cawood in Happy Valley.
The BBC crime drama aired its second series last year, although, fans will have to wait a long time for the next instalment.
Speaking to Express.co.uk recently, Sarah said: “It’s been a pretty long time now. I know she wants to do a third series but she’s so busy writing other stuff we’re kind of in a queue.
“When she feels the time is right, we will do a third. Which I am looking forward to. I am ready to play her again. I can’t breathe.”
The popular actress also revealed that she nearly quit the role just four weeks into filming the first series.
Sarah explained: “For the first four weeks I kept telling them, I am wrong for this role.
“I couldn’t find a way to feel comfortable. I didn’t feel comfortable with the uniform. I thought I’d just be an actor in a uniform.
“I was worried about the accent. I was scared the accent was coming across as too broad. But they told me to trust them and I did.”