Would you disconnect yourself from the world and retreat to a dark cave for 40 days? 

In France, 15 people did just that, emerging Saturday, from the scientific experiment, slightly disoriented, saying that time seemed to pass more slowly in the cave, where they were deprived of clocks and light.

The group left their voluntary isolation in the Lombrives cave to a round of applause and basked in the light while wearing special glasses to protect their eyes after so long in the dark.

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"It was like pressing pause," said Marina Lançon, one of the seven female members in the experiment, adding she didn't feel there was a rush to do anything.

Although she wished she could have stayed in the cave a few days longer, she said she was happy to feel the wind blowing on her face again and to hear the birds sing in the trees of the French Pyrenees. And she doesn't plan to open her smartphone for a few more days, hoping to avoid a "too brutal" return to real life.

Lost their sense of time

For 40 days and 40 nights, the group lived in and explored the cave as part of the Deep Time project. There was no sunlight inside, the temperature was 10 degrees Celsius and the relative humidity stood at 100 percent. The cave dwellers had no contact with the outside world, no updates on the pandemic nor any communications with friends or family.

Scientists at the Human Adaptation Institute leading the $1.5 million Deep Time project say the experiment will help them better understand how people adapt to drastic changes in living conditions and environments.

As expected, those in the cave lost their sense of time.

"And here we are. We just left after 40 days... For us it was a real surprise," said project director Christian Clot, adding for most participants, "in our heads, we had walked into the cave 30 days ago."

At least one team member estimated the time underground at 23 days.

Johan Francois, 37, a math teacher and sailing instructor, ran 10 kilometer circles in the cave to stay fit. He sometimes had "visceral urges" to leave.

With no daily obligations and no children around, the challenge was "to profit from the present moment without ever thinking about what will happen in one hour, in two hours," he said.

Most wanted to stay underground longer 

In partnership with labs in France and Switzerland, scientists monitored the 15 members' sleep patterns, social interactions and behavioral reactions via sensors. One sensor was a tiny thermometer inside a capsule that participants swallowed like a pill. It measured body temperatures and transmitted data to a computer until it was expelled naturally.

The team members followed their biological clocks to know when to wake, sleep and eat. They counted their days not in hours but in sleep cycles.

On Friday, scientists monitoring the participants entered the cave to let the research subjects know they would be coming out soon.

"It's really interesting to observe how this group synchronizes themselves," Clot said earlier in a recording from inside the cave. Working together on projects and organizing tasks without being able to set a time to meet was especially challenging, he said.

Although the participants looked visibly tired Saturday, two-thirds expressed a desire to remain underground a bit longer in order to finish group projects started during the expedition, Benoit Mauvieux, a chronobiologist involved in the research, told AP.

"Our future as humans on this planet will evolve," Clot said after emerging. "We must learn to better understand how our brains are capable of finding new solutions, whatever the situation."

Video editing: Sam Cordell