Beatriz Flamini emerged smiling from an underground cave in Spain on Friday, where she had spent 500 days living in isolation, saying the time had flown by.

"When they came in to get me, I was asleep. I thought something had happened. I said, 'Already? Surely not.' I hadn't finished my book," the 50-year-old Spanish athlete said, according to the Reuters news agency.

Flamini went underground as part of an experiment to allow scientists to learn more about circadian rhythms and the human mind, Reuters reported. She was closely monitored by psychologists, physical trainers, cave specialists and other researchers, though no one was permitted to make contact with her.

"It's not that the time passes more quickly or more slowly, simply that it doesn't pass, because it's always four in the morning," Flamini filmed herself saying during her days underground. 

"It's been amazing, girl. It's been really amazing," she told the camera.

She spent two birthdays in isolation, missing a year of war in Ukraine and the death of Queen Elizabeth II. She said she spent her time reading, painting, doing exercises, knitting hats and trying to maintain "coherence."

According to Spanish news agency EFE, Flamini was being studied by scientists at a sleep clinic in Madrid, as well as at universities in Granada and Almeria, to determine the effects of isolation and extreme disorientation on the perception of time and the effects of being underground on sleep patterns.

"I love you so much," Flamini told her support team as she emerged Friday. "I'm really grateful, and please disregard anything I have said down there." 

Flamini said she would be examined by doctors so they could assess the physiological effects of her time in the cave before she embarked on any new caving or mountaineering projects, Reuters reported.

Haley Ott

Haley Ott is an international reporter for CBS News based in London.

Twitter