Welcome to Spotlight Advanced. I'm Marina Sante and I'm Patrick Woodward. Spotlight uses a special English method of broadcasting. It is easier for people to understand no matter where in the world they live. A group of people crowd around a large hole in a rock. A rope hangs down into the hole. Soon the rope moves. A man comes out of the hole, wearing a hard hat and climbing equipment. The man in the hard hat has his arm around
another man. The first man moves very weakly and he is only just able to climb. He closes his eyes as he enters into the light. It is too bright for him. He has not seen the sun for six months. This man's name is Michel Siffe. He is a French geologist. A geologist is a person who studies the earth. But today Sife is not studying the earth. Instead, he is studying how people experience time. Sife locked himself away under the ground for half a year. He did not have clocks,
he did not have the sun to tell him when to sleep. He slept as long as he needed, and he stayed awake as long as he wanted. The experiment was very bad for him, It troubled him a lot, but while living underground, Michele Siffe discovered something very important, the internal clock. Today's spotlight is on Michell Sife and the internal clock. Sief did not train to study how people experienced time. Instead, Sieff went to school
to be a geologist. As a young man, he explored underground and studied different kinds of rocks but wonder In nineteen sixty two, seef explored a cave that would change his life. He had discovered an underground glacier. The glacier was in the French Alps. He was supposed to lead a trip to the mountains to study the glacier. The trip was to take fifteen days, but
Siefe did not believe that this was enough time. He decided that he would go for two months instead, and as an experiment, he would go without bringing a clock. He would live in the cave alone. His goal was to have no connection to time passing in the outside world. He wanted to see what his body would do. Joshua Foeher is a writer. He spoke to Michelle sief about his experiment. Seif said, I invented a simple scientific
method. I put a team at the opening of the cave. I decided I would call them when I got up, when I ate, and just before I went to sleep. My team did not have the right to or me. I would have no idea what time it was. The cave was not a great place to live, living near a glacier. See If was often wet. His body temperature would get very low. It would go as low as thirty four degrees celsius. He also did not have much to do. He studied the glacier, He read his books and wrote in his journal,
but there was no one to talk to. He lived by himself and lost all sense of time. See If told Joshua Foreua, there were two tests I did every time I called the surface. First, I checked my heart beat. Second, there was a mental test. I had to count from one to one hundred twenty. I counted at a rate of one number each second. With that test, we made a great discovery. It took me five minutes to count to one hundred twenty. In other words, I
experienced five real minutes as if they were only two minutes. When two months had passed, Siefe's team called him. They told him it was time to leave. Seefe was very confused. He was supposed to leave on the fourteenth of September, but he believed that it was only the twentieth of August. He had lost twenty five days. But Sefe also discovered something even more amazing. He discovered that each of us has an internal clock. This clock tells
our bodies when to sleep and get up. Usually, we sleep and get up because of light from the sun, we live in a twenty four hour sleep cycle. Sefe also lived in a cycle, but his sleep cycle was twenty four and one half hours long. This proved that the sun was not the only thing organizing sleep. Instead, humans have a natural cycle without the sun. We sleep and get up when our bodies tell us to. Siff knew that what he had discovered was very important, so he devoted his life
to studying this eternal body clock. In fact, he is considered the father of the new field of study called chron biology. Chron Biology studies how these internal cycles of time affect both mind and body. He performed many other experiments. In some he sent other people into caves. They also stayed for months. These people had different sleep cycles than Sief did. Instead, they developed
forty eight hour cycles. They would stay awake for thirty six hours, then they would sleep for twelve This meant that each person's sleep cycle was different, and most are longer than twenty four hours. These experiments were very important at the time. Countries had just begun to send people into space, but no one knew how going to space would change people. They did not know how
it would affect sleep. Being alone in a cave is a little like being alone in space, so people going to space could prepare better for the effects of traveling in space on their bodies. Then, in nineteen seventy two, Sieff decided to do another experiment on himself. He would go down into a cave again. He was older and he wanted to study how this changed the results, but he also wanted to stay underground longer. He would live in
the cave for six months. Thief's six months underground affected him very differently than before. Two months underground did not change him much, but the six months caused him great mental disturbance. He began to fear the fungus that grew on the cave walls. He feared he would catch diseases from the cave dust, and he felt extremely sad. Once he was so lonely that he tried to
befriend a mouse. He tried to catch the mouse so he would have something living to talk to, but he was not able to He killed the mouse by accident. This made him so sad he thought about taking his own life, but he continued with his experiments. He did not give in to his sadness. By the end, he could only say a few words and it was very difficult to think. Sef had everything he needed to survive, but without others, his mind stopped working well. Sief's experience damaged his mind,
but this experiment was a success. His discoveries helped inform scientists how sleep works, and he helped confirm the importance of physical touch. Being touched by other people is not just nice, It is important to survive. People can survive without other people for a long time, but it can be dangerous to their health. After his six months stay, Sief stopped his experiments for eight years. He moved away from his home in France and divorced his wife. His
time in the cave changed him. He needed time to recover. Soon though, Sief began experimenting again, and today he is one of the most well known people who study time. His experiments are still the only ones of their kind. Franz Halberg is a professor at the University of Wisconsin. He also studies how we experience time. In nineteen eighty eight, he spoke to the Los Angeles Times about Sife. He said, some people think he's a bad boy, but Sief does what no one else will do. He has by
far the longest records of people being alone. Others who have studied similar things have done it for weeks. He has done it for months. Would you live by yourself for two months? What about six months? Why? Or why not? You can leave a comment on our website or email us at Radio at Radio English dot net. You can also comment on Facebook at Facebook dot com slash Spotlight Radio. You can also get our programs delivered directly to
your Android or Apple device through our free officials Spotslight English app. The writer and producer of this program was Dan Christman. The voices you heard were from the United Kingdom. All quotes were adapted for this program and voice by Spotlight. You can listen to this program again and read it on the internet at www dot Radio English dot net. This program is called Living Without Time, Michelle Siefe and the internal clock. We hope you can join us again for
the next Spotslight program. Goodbye du