Who, What, Why: How unhealthy is three-and-a-half years indoors?

Julian Assange has made public appearances, but only on a videolink

Julian Assange has been in the Ecuadorian Embassy in London since June 2012. There's long been speculation about the state of his health, so how unhealthy is a prolonged period indoors?

The Wikileaks founder took refuge in the embassy to avoid extradition to Sweden to face questioning over alleged sex assaults. He faces arrest if he leaves the building.

Assange has previously said that he had no access to outside areas. Even healthy people would have difficulty living inside for so long, he said.

Past media reports have suggested he needs treatment for a range of health problems - arrhythmia, high blood pressure and a chronic cough.

The biggest implication for physical health of being inside for so long is vitamin D deficiency, explains Sarah Jarvis, doctor for the BBC's One Show. About 85-90% of people's vitamin D comes from sunshine. Dozens of conditions have been associated with low vitamin D levels, from depression and aches and pains to osteoporosis and heart disease.

There is of course the option of taking Vitamin D tablets, which are widely prescribed to millions of people who don't get enough sunlight - but evidence of how effective they are is insufficient, says Jarvis. "Is taking supplements as good as getting it (Vitamin D) from sunshine? We don't know," she adds.

A sunbed or UV lamp would work but over a period of years this would be inadvisable, said Simon Griffin, professor of general practice at Cambridge University, speaking in 2014. Sunbeds are linked with melanoma, a form of skin cancer. Assange has already spoken of a "boiled lobster" moment from a sunlamp.

It's unlikely that a couple of years inside would damage the body greatly if someone took action to make sure they were getting some daylight, exercise and eating a healthy diet, said Griffin. Air conditioning is unlikely to harm Assange. The most likely harm would be a flattening of mood, Griffin said. Sunlight makes people feel happier. There is a balcony at the embassy - Assange has occasionally addressed supporters from it. Even just exposing face and forearms to the sun regularly would help avoid feeling down, Griffin said.

Julian Assange in August 2014 and in February 2012

One thing that's impossible to gauge is Assange's mental state. He's been isolated for a long time, says Geoff Beattie, professor of psychology at Edge Hill University. "He may have been able to talk to friends on the phone or via Skype, but that's not the same as person to person contact," Beattie adds. On top of that, Assange will have been living with in a state of uncertainty with the threat of extradition hanging over him.

"This is very stressful and will take a big toll on his physical and mental health," says Beattie. Combined with his isolation, it may have led to him ruminating too much on his situation, which can cause depression, Beattie adds. "Living in such close proximity to the same people for so long, as he will have done with the embassy staff, is not ideal either."

However, Sandi Mann, a psychology lecturer at the University of Central Lancashire and author of the soon-to-be-released The Upside of Downtime, a book which looks at how boredom can sometimes be a bonus, says having nothing to do can sometimes be positive: "It gives people time to reflect, to look inwards, and this can lead to positive change."

A previous version of this story was published in August 2014.

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