Barrowman, who plays Captain Jack Harkness in the series, revealed that he and partner Scott Gill are more content to relax at home than go to a trendy nightclub.
"I can't handle clubs and wild nights out like I did in my 20s. I'm lively when I perform and I always put everything into a show but when I get home I love lying down in front of the TV and relaxing," Barrowman told The Mirror.
The Scottish-born actor added: "I'm not quite the party animal people imagine. I'm certainly not a big fan of nightclubs. But that doesn't mean I don't enjoy a vodka and tonic or two after a tough day."
Barrowman began dating Gill while starring in a production of Rope in 1993. The couple became civil partners in December 2006.
Barrowman recently suggested that he is annoyed when television stars complain about being famous.
Torchwood: Miracle Day continues Thursday at 9pm on BBC One, and airs this Friday at 9/8c on Starz in the US.
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Watch John Barrowman discuss Torchwood: Miracle Day with Digital Spy below: