Martin Sheen says his wife is the "scariest woman" he's ever met.

The 74-year-old star says the secret to his 50-year marriage to the actress Janet Templeton, whom he married in 1961, is that she was never afraid to tell him the truth.

He explained: "I was fortunate enough to marry the scariest woman I'd ever met. She did not know how to lie. It was impossible. For me, the truth was a sometimes thing. For her, it was eternity. She would always call me out, thank God."

The 'West Wing' actor famously suffered a heart attack on the set of his 1977 film 'Apocalypse Now' due to his heavy drinking but he failed to get sober until ten years later and he's confessed they were hard times for him and his wife, with whom he had his children Charlie Sheen, Emilio Estevez, Ramon Estevez and Renee Estevez.

Asked if Janet had her work cut out for her, Martin shared: "Yeah, it wasn't very endearing. I was a known alcoholic, and obviously troubled in a lot of areas."

Martin - who describes himself as a "prude" - has now been sober for almost 30 years thanks to Alcoholics Anonymous and his return to the Catholic Church, but neither of those institutions have affected his liberal attitude.

Speaking about gay marriage, he told Radio Times magazine: "I am not against anybody expressing their love to anyone else; it's none of my business."