Adventurer Aldo Kane has taken part in a gruelling scientific experiment which saw him spend ten days holed up in an abandoned nuclear bunker in Devon without sunlight, human contact or any way of telling the time.

The bunker was rigged with cameras to monitor Kane, 40, from Kilwinning, and he was asked to carry out daily tests to measure everything from his mood to his reaction time and memory. Academics created the experiment to understand what drives our internal body clock when it’s cut off from the outside world.

Kane said: “In the first couple of hours what struck me most was how deafening silence is. The bunker is underground, it’s soundproof. The white noise was just phenomenal, and it never left the entire ten days. Any noise that I made scared me because you’re not used to that quietness. You’re there with your own thoughts and nothing else, and that’s terrifying. And it was damp and cold and dark.”

Evolutionary biologist Ella Al-Shamahi, who oversaw the experiment, said: “Altering our daily rhythms is bad for our health. Studies on shift workers show that if we regularly disrupt our sleep, we’re at a greater risk of diabetes, heart disease and cancer. So, understanding our biological clock couldn’t be more important. To do that we need to strip away the trappings of modern life and even the natural rhythms of sunrise and sunset.

“Experiments like this have driven participants out of their minds.”

In a documentary about the experiment, to be shown on BBC Two this week, Kane is seen growing increasingly confused and frustrated as the isolation and darkness led to a deterioration of his mental health.

Kane said: “I was feeling more and more down because I was not exercising properly and was not getting daylight. I’m also a social person and I enjoy the company of other people. Without those three things, I found myself getting to the point where I could see how I could slip into depression or anxiety if that isolation had continued beyond the ten days.”

In day three of the experiment, control of the lights in the bunker was taken away from Kane and he started taking unexpected naps because he had no way of knowing the time of day.

By day four, Kane thought he was in day five. His sleeping pattern became more and more erratic, he began to struggle to concentrate on simple tasks and he found it increasingly difficult to exercise.

His biological clock effectively moved thirty minutes every day, meaning he was going to bed later and getting up later.

In the later stage of the experiment, Kane was woken at 6am – in the middle of his night – for the “jet lag phase”. Al-Shamahi said: “It’s as if he’s flown from New York to London.”

She saw Kane’s reaction speed, physical performance and mental ability “take a nosedive”. “That’s because his body is completely out of sync,” she explained. “He’s active when he should be resting and resting when his body is ready to be active. Long term this misalignment can harm the health of shift worker and regular jet lag sufferers. There’s a strong link to mental health, too.”

As the end of the experiment approached, Kane was confused about how many hours remained. He said in the documentary: “I have a small, niggling worry that this may not actually be day nine…it is doing my head in.”

Kane is seen roaring with frustration. “You can see how easy it would be to unwind psychologically,” he said.

He was free to leave the bunker at any time, but as a former Royal Marines Commando who survived tours of Iraq and Afghanistan, he was determined not to give up. “Me being me, I was loathe to do that,” he said.

At the end of the experiment he emerged blinking into the sun at the height of summer, and immediately had to put on sunglasses to cope with the glare.

Kane said: “It was like The Matrix. My senses were heightened. I could almost smell individual plants around the bunker.”

Later that day he was on a flight to Greenland to film a documentary with naturalist Steve Backshall.

“Eight hours coming out of the bunker I was standing in a fjord at two o’clock in the morning in broad daylight thinking, what the f**k has just happened,” he said.

Al-Shamahi added: “What Aldo put himself through inside the bunker was completely extreme, but from an evolutionary perspective, the way most of us live now is also extreme.

“We spend all day inside dingy offices and use artificial light way into the night. What’s worse is we live by schedules which force us all – whether we’re early birds or night owls – to live by the same clock.

“It’s not how we’re built and it’s why our body clocks get confused and have problems.”

Body clock: what makes us tick? Will be broadcast on BBC Two Scotland on Thursday.

KANE IS THE ‘COOLEST’ SCOT

Aldo Kane was recently named the coolest Scot in the Herald on Sunday’s Cool List of the top 100 “movers, shakers and rule breakers”.

He discovered he had topped the list while in South America filming a documentary with naturalist Steve Backshall.

Kane said: “I was in the jungle in deepest, darkest Suriname and all I had was a satellite phone – I can’t describe to you how remote it was – and I got a text from my girlfriend back home which said: ‘You’re the coolest person in Scotland!’”

When Kane told the team in South America he got some stick. “I told Steve and all the rest of the guys and they were like: “yeah, whatever. P*ss off,” said Kane, laughing. “But, really, they thought it was brilliant. And I was so chuffed.”