We all know it. Every morning we lack an hour to really get a good night's sleep. But what is it? Are there internal clocks that tick a little differently than our official ones? Is it possible that our biorhythm is still set for ancient times, when one day did not last 24 hours, but more or less? These questions were asked by a team of scientists in Germany who conducted a unique experiment that lasted over 20 years and for which a special bunker was built.
Without watches, daylight, and connection with the outside world
One of the most important rhythms for humans is the alternation of day and night. But what if we are isolated from this rhythm? Do we still know what time it is? A famous experiment in the 1960s traced our internal clocks: Volunteers went into a closed bunker for several weeks. The facility was purpose-built and had all the equipment except for two things: there was no daylight and no way to tell the time. Till Roenneberg, professor of chronobiology at the LMU in Munich, accompanied the experiments in the bunker.
Prof. Till Roenneberg: "The experiments in the bunker were actually something very exciting from the point of view of the history of science. We already knew from plants and animals that there are internal clocks that are controlled mainly by light, since we always assumed in humans that nature no longer cares about us no influence, only social life, it was necessary to build an experimental apparatus, which was then a bunker, in which everything that could indicate any time signals was enclosed.'
The protection from the outside was massive, reinforced concrete, with walls one meter thick. The then head of the Max Planck Institute, one of the founders of bunker experiments, was Jürgen Aschoff. In 1966, the first test persons ventured beyond the thick walls. Jürgen Zulley took over the management of the bunker experiments in the 1970s and they ended in the early 1980s. Big brother is watching you - Big brother on camera.
Jürgen Zulley, sleep researcher, University of Regensburg: "Most of them went with a certain tension at first, whether it could be sustained at all. After two or three days, however, they realized that it was not really a question. They were very comfortable to put up with. And they didn't want to go out at all."
Prof. Till Roenneberg: "We measured a lot of things, for example, there were contacts in the ground to measure walking, we could measure the switching on and off of every light. People wore - something unpleasant - rectal temperature probes. They had a lot of work, they had to write down what and when they eat, and they had to ring the bell every hour - whenever they thought it was the hour, and then again a minute later to share their long-term and short-term estimates.'
Subjects allowed their sense of time to flow freely, going to sleep when they were tired and getting up when they woke up. The daily regime, at least in terms of time use, was similar for everyone. About one-third is sleep, two-thirds is wakefulness. In hours, that's 8 hours of sleep and 16 hours of wakefulness.
Jürgen Zulley: "The end of the experiment always went like this: A message was given to the participant, where it was written that we were coming for a visit. They didn't know why, and when we arrived, we first asked him what day it was, what time it was. They were always wrong, bad they estimated. They were told the experiment was over. Most didn't like it at all, they would have preferred to stay longer."
The result was as everyone expected
Prof. Till Roenneberg: "It turns out that people also have a circadian internal clock, which you can see especially well if you leave out all the information from the outside world, so they develop their own dynamics. They don't fall into chaos but make their own day. And that's usually not exactly 24 hours, but something like 25 hours."
Jürgen Zulley: "The most extreme case was that the test person was in the bunker for five weeks, but according to his own calendar only three weeks had passed. So-called circadian days appeared, in this case, 50-hour days. And the interesting thing was that the person had the hardest time coming to terms with that, that he suddenly lacked two weeks of life."
Circadian rhythm
The circadian rhythm is a biological rhythm with a period of 20-28 hours. The circadian rhythm is one of the biorhythms, i.e. the fluctuation of activity and alertness most often within a daily, monthly, or yearly period. The pioneer of this concept is the Romanian scientist Franz Halberg, but the phenomenon has been known since ancient times.
You must be logged in to post a comment.