“When I first met him I thought, ‘No way can I use such a character who’s so extreme,’” says Electric Malady director Marie Lidén. “But then after spending half an hour with William I stopped seeing the fabric and just started seeing this guy, this down-to-earth, poetic guy.’”

The Scottish-based Swedish filmmaker is talking about the subject of her documentary, William Hendeberg, a sufferer of electrosensitivity, a rare condition that effectively makes those who experience symptoms allergic to the modern world. As a result, William — who in the film likens its effect to having his head in a vice — lives a very isolated life in a cottage in the Swedish countryside where he sleeps in a makeshift Faraday cage, rarely goes outside and spends most of his days cloaked under layers of copper-lined cotton fabric designed to limit his exposure to the microwave radiation that’s increasingly a by-product of our digitally interconnected world. His father affectionately refers to him as "the ghost", and Lidén’s trepidation about using him in the film was out of fear of making William seem like a freak and undermining her effort to shine a light on a controversial condition that is little understood. “He has this floaty way of moving through his cabin that’s quite beautiful,” she says. “At the same time, he’s like, ’It’s not beautiful. It’s horrible.’ He’s quite ashamed of how he looks.”

Eliminating the stigma is one reason Lidén — whose mother used to be electrosensitive — wanted to make the film. It’s also the main reason William and his family wanted her to tell their story, even though filming risked making William feel unwell. “I know there were times he’d have to spend a whole day recovering after we were there,” she says. To minimise the distress, she’d use a small DSLR camera and keep her distance from him as much as possible, but he also seemed okay with a hand-cranked Bolex film camera, something that gives the film its appropriately tactile, analogue aesthetic.

William Hendeberg, a sufferer of electrosensitivity, in Marie Lidén's documentary, Electric Malady.

When I meet Lidén it’s the day after Electric Malady’s EIFF premiere (there’s another screening at the Festival today) and she’s just happy the ten-years-in-the-making film seems to be connecting with audiences. “I’m so glad it travels, because I wasn’t sure how people in the UK would react to the film. And I was terrified I’d be attacked by people who didn’t believe this is real.”

“But it’s interesting,” she adds. “I feel like lockdown really changed people's perception of loneliness and isolation. And I feel like the response that people are having to the film now is very much that they feel a connection to his situation.” Alistair Harkness

Electric Malady screens on 18 August. For more information and tickets, see edfilmfest.org.uk

Edinburgh International Film Festival Diary: 18 August