The 28-year-old actor, who plays Gary Windass on the ITV soap, and his fiancee Rachael Isherwood discussed the issue while filming the new series of "All Star Mr and Mrs", reported Digital Spy.
"I'm a terrible, terrible sleepwalker. At some point one of our neighbours is going to come home from a night out and see Gary Windass there with his Y-fronts on," North said.
Isherwood also spoke about the problem, adding: "I sometimes catch him leaving the flat in his underpants!"
The new series of "All Star Mr and Mrs" will air on ITV in the autumn.