An Italian sociologist has taken up residence in an underground cave, where he is hoping to spend the next three years of his life.
The sociologist has already broken world records for living in caves
Maurizio Montalbini hopes his efforts will help scientists better understand the body's natural cycles.
The 53-year-old, who moved into his cave home on Wednesday, spent just over a year living in a cave in the 1990s.
Although he plans to nourish himself with food pills, he has also brought supplies of honey, nuts and chocolate.
Mr Montalbini, a keen caver, will drink water from a small pipe during the more than 1,000 days he will spend underground.
But he is not worried about missing out on lasagne. In fact he suspects the days will fly by too quickly.
4kg (10lb) honey
2kg (4.4lb) nuts
1.5kg (3.3lb) chocolate
"I've signed a letter authorising those who monitor me outside, my friends from the underground laboratory, Underlab, to let me spend three years in the grotto, no more," Mr Montalbini told Italy's La Repubblica newspaper.
In an earlier attempt, Mr Montalbini's sense of time was shifted by a lack of exposure to natural light.
"When I remained 366 days underground, I had the impression of only spending 219 days," he said.
"This is the last experiment I'm going to do, I'm getting too old for this," Mr Montalbini added.
The cave measures 2m (6.6ft) in width, 50m (164ft) in length and 5m (16.4ft) in height and is situated some 80m (262ft) underground.
It was not immediately clear which caves the sociologist had chosen for the experiment, but similar tests have taken place at caves in the Marche region of central Italy.