Light is an important source to our brains. It often helps tell us what time of day it is and whether we should go to sleep or not based on this information. What would happen to our sleeping pattern if we had no indication if it was day or night? Would we still have a regular schedule? A French adventurer and scientist, Michel Siffre, sought to find out.
- We are going to explore Siffre's cave study in psychology.
- First, we will discuss the biological rhythms Siffre's cave study is investigating.
- Then, we will explore Siffre's cave study aims before highlighting Siffre's cave study findings.
- To help summarise the information, we will also provide Siffre's cave study summary.
- Finally, we will discuss the strengths and weaknesses of Michel Siffre's cave study through an evaluation.
Michael Siffre's Cave Study: Psychology
Michel Siffre, a french adventurer, investigated how the absence of external cues could affect biological rhythms, namely, how a lack of light may interrupt his circadian rhythm. Siffre spent months in a cave without access to daylight and found his circadian rhythm was notably disrupted.
Fig. 1 - Michel Siffre explored how a lack of light affects our circadian rhythms.
Siffre's Cave Study and Biological Rhythms
We have a regular sleep/wake pattern on a 24-hour day due to biological rhythms – internal biological clocks in our body that govern different bodily functions/cycles. Siffre was interested in how a lack of external cues could disrupt our bodily rhythms, namely, the circadian rhythm.
The circadian rhythm lasts for 24 hours. A well-known circadian rhythm is a sleep-wake cycle. This cycle is our pattern of sleeping and wakefulness during a 24-hour day. Everyone's sleep-wake cycle is different, and different things can affect the sleep-wake cycle, such as external cues.
These external cues are called exogenous zeitgebers, and the most notable one affecting the sleep-wake cycle is daylight.
Biological rhythms
Internal biological clocks in our body govern different bodily functions/cycles.
Circadian rhythm
A biological rhythm that lasts for 24 hours. An example of a circadian rhythm is the sleep-wake cycle.
Exogenous zeitgebersExternal cues from the environment that influence biological rhythms An example of an exogenous zeitgeber that influences the sleep-wake cycle is daylight.
Fig. 2 - Biological rhythms govern our bodily functions, including sleep.
Siffre's Cave Study: Summary
Siffre's cave study can be summarised in the following table. Here, we can see the timeline of what happened in the study and how Siffre attained his findings.
- Michel Siffre is an adventurer and scientist interested in the study of caves. In 1962, at 23 years old, he decided to live in a cave alone in the French Alps for two months, which was partly due to finding a glacier there sometime before he wanted to study.
- He then thought of living without any natural light, without knowing what time it was. So instead of studying the glacier, he ended up studying time. He spent his time in the cave reading, writing, researching, and thinking about the future. He settled into a sleep-wake cycle of around 24 hours and 30 minutes.
- He went into the cave on 16 July 1962 and came out of the cave on 14 September 1962. However, Siffre thought the day he came out of the cave was the 20 of August, showing how his time in the cave had warped his sense of time.
- Afterwards, Siffre also had other people participate in cave experiments but found their sleep-wake cycle was 48 hours. Siffre wanted to see if he could also get his sleep-wake cycle to be 48 hours. In addition, this was when people were starting space exploration, and Siffre thought his cave studies could help us know the experiences astronauts go through, which might be similar to being in a cave.
- So, in 1972, when he was 33 years old, he decided to live alone in a cave again – this time, for six months.
Siffre Cave Study in Psychology: Aims
The aims of the study were to find out what it would be like for astronauts in space, where there were no exogenous zeitgebers such as daylight to affect our biological rhythms. Siffre wanted to find out what his natural sleep-wake cycle would be without any exogenous zeitgebers.
Siffre Cave Study in Psychology: Procedure
On 14 February 1972, Siffre went into Midnight Cave, Texas, USA and stayed there for six months. He stayed in a tent with a bed, table, and chair.
- He took a supply of frozen food and 780 gallons of water into the cave.
- When Siffre woke up and thought it was daytime, he phoned the research team above ground, and they switched on the lights in the cave.
- He conducted daily experiments, taking his blood pressure, memory, and physical tests. When he felt tired, he thought it was then nighttime; he would phone the research team again, informing them he thought it was night and they would turn the lights off, and Siffre would go to sleep.
Siffre Cave Study in Psychology: Findings
After some time in the cave, Siffre became depressed and despondent at his lack of freedom. He was also excruciatingly lonely, he wanted to trap a mouse so he would have some companionship, but in the process of trapping it, he accidentally killed the mouse. In his own words, 'Desolation overwhelms me.'
In addition, his record player broke, and his books got ruined due to dampness. His condition was so dire that Siffre thought of suicide. His short-term memory, mental health, and eyesight all got worse.
Here is an account of his experience in the cave:
Overcome with lethargy and bitterness, I sit on a rock and stare at my campsite in the bowels of Midnight Cave, near Del Rio, Texas. Behind me lie a hundred days of solitude; ahead loom two and a half more lonely months. But I - a wildly displaced Frenchman - know none of this, for I am living "beyond time," divorced from calendars and clocks and from sun and moon, to help determine, among other things, the natural rhythms of human life.—Siffre (1975)
For the first 35 days, Siffre had a sleep-wake cycle of 26 hours.
On day 37, he stayed up for a few more hours and then slept long. This pattern of being awake and then asleep for a long time occurred periodically for the next month.
Then on day 63, he returned to a cycle of 26 hours. Nine weeks later, his sleep-wake cycle became more varied and random again for 20 days.
Sometimes it was 48 hours as the people in previous studies. When his sleep-wake cycle varied, the cycle could be from 18–52 hours. On day 150, he returned to a 26-hour cycle that lasted until the experiment's end.
Fig. 3 - Michel Siffre spent six months in a cave to study the sleep-wake cycle.
Siffre Cave Study: Conclusion
Siffre thought astronauts could manage their biological rhythm without exogenous zeitgebers; however, they would need companionship as the isolation would not be manageable. Siffre concluded that time is not something humans could work with and understand without any external environmental cues.
Michel Siffre Cave Study in Psychology: Evaluation
Let's look at the strengths and weaknesses of Siffre's (1975) study.
Siffre Cave Study: Strengths
First, let's explore the strengths of Siffre's cave study.
The study produced a lot of quantitative and qualitative data.
The study was done over a long time, six months, which allowed Siffre to investigate his sleep-wake cycle and show how irregular it became.
Siffre Cave Study: Weaknesses
When Siffre woke up, strong lights were put on, and when he went to sleep, they were turned off. The lights could have acted as an external cue, which affects the study's internal validity.
Siffre was the only participant in the study, so it is hard to generalise his findings, such as how he did to astronauts.
Siffre Cave Study Psychology - Key takeaways
- We all have a sleep-wake cycle, a biological rhythm (internal body clock). Exogenous zeitgebers can influence biological rhythms (external cues from the environment).
- Siffre conducted an experiment where he spent six months alone in a cave. He aimed to discover what it would be like for astronauts in space, where there were no exogenous zeitgebers such as daylight to affect our biological rhythms. Also, what his natural sleep-wake cycle would be without any exogenous zeitgeber.
- When Siffre woke up and thought it was daytime, he phoned the research team above ground, and they switched on the lights in the cave. He conducted daily experiments, taking his blood pressure, memory, and physical tests. When he felt tired and thought it was nighttime, he would phone the research team again, they would turn the lights off, and Siffre would go to sleep.
- Siffre became depressed, and his short-term memory, mental health, and eyesight worsened. His sleep-wake cycle varied a lot. For some periods, it was a fairly regular 26 hours. However, it could range from 18 to 52 hours.
- Siffre concluded that although his biological rhythm was inconsistent without any external cues, it was still manageable. Regarding astronauts, Siffre thought that they would be able to manage their biological rhythm without any cues; however, they would need companionship. Siffre concluded that time is not something humans could work with and understand without any external environmental cues.
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