Kit Harington had "lost his way" before checking into rehab.
The Game of Thrones star checked into a treatment facility last month after the ending of the hit HBO show - on which he starred as Jon Snow - "really hit him hard", and now a costume designer for the programme has said it was clear leaving the show behind affected him, because he was always a "sensitive soul".
Michele Clapton told Us Weekly magazine: "They were children when they started. And it became such an enormous thing, and I think when you stop, it's sort of a huge security blanket is taken away.
"I mean, they all became friends with each other, and then suddenly, there's nothing to go back to. So I would imagine that had something to do with it. He lost his way a bit.
"He was really a sensitive soul, and he was very upset in that final read through because I think it felt like home for [the cast], and they realised, 'This is it.'"