The 45-year-old star, who played boozy 1960s adman Don Draper in beloved TV show Mad Men, spent 30 days in treatment for alcohol addiction last year (15).

In September (16), months after his rehabilitation stint, the star and his long-term girlfriend Jennifer Westfeldt, 46, announced they were splitting after 18 years together.

Despite a year of personal turmoil, Jon credits his time in treatment combined with weekly visits to a therapist with helping him overcome his problems.

"It (rehab) has all these connotations, but it's just an extended period of talking about yourself," he tells British menswear retailer Mr Porter's The Journal magazine. "People go for all sorts of reasons, not all of which are chemically related. But there's something to be said for pulling yourself out of the grind for a period of time and concentrating on re-calibrating the system. And it works. It's great."

The star is an evangelist for the merits of therapy, having first attended sessions after his father died when he was 20 years old.

"I find it (therapy) very helpful," he explains. "I know the English are a lot more sceptical about it than Americans are, but maybe after Brexit (Britain leaving the European Union), you'll change your minds," he joked.

After a troubled period, Jon's sister convinced him to get professional help, and he has the same advice for others, provided they can afford to.

"After I'd lost my dad, I had this horrible paralysing inertia - and no one in my family was capable of dealing with it," he adds. "So what do you do? Go and see a professional.

"I preach it from the mountaintops. I know it's a luxury and it's not something everyone can afford. But if you can, do it. It's like a mental gym."

Jon's latest film Keeping Up with the Joneses, which sees him play a spy who gets mixed up in the lives of a suburban couple, played by Zach Galifianakis and Isla Fisher is released on 21 October (16).