I am toying with an idea which requires a human to be stuck in a dark box for the rest of their life.

They receive regular exercise of the arms and legs, air, food and water and their bodily functions are taken care of by the box.

The only contact they have to the outside world is through a pair of binoculars and hearing trumpets. They have contact with humans, but cannot respond.

How long can someone survive with only movement, sight and hearing of the outside world, air, food and water?

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    $\begingroup$ Make sure they have enough Vitamin D additives in their food, as they won't have sunlight to make it. $\endgroup$
    – Eth
    Commented Jun 14, 2019 at 15:54
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    $\begingroup$ how are they able to get adequate exercise in complete darkness? This may seem a given but it would be exceedingly simple to injure oneself trying to maintain a healthy activity level without being able to see. Accumulation of these injuries could greatly reduce lifespan $\endgroup$
    – BKlassen
    Commented Jun 14, 2019 at 17:09
  • $\begingroup$ @BKlassen I can sure safely ride a bike in various degrees of darkness, depending on how well it is screwed to the floor. $\endgroup$
    – Karl
    Commented Jun 14, 2019 at 20:38
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    $\begingroup$ @karl I bet you have difficulty walking on a mattress in total darkness though. Please don't try this for real without holding onto something, it's extremely easy to fall. $\endgroup$
    – Innovine
    Commented Jun 14, 2019 at 21:46
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    $\begingroup$ Blind people can exercise. Assuming the conditions inside the box allow for it, being able to see isn't required for physical activity without falling down (though there would be a learning curve). $\endgroup$
    – Cyn
    Commented Jun 16, 2019 at 3:30

5 Answers 5


On a sustainable diet, theoretically they would live a semi normal life expectancy. Physiologically, all of their needs would be met, however psychologically, this is a different story. By nature, humans are social creatures who depend on social interaction. If a person was never to have seen the outside world, they would take on an Allegory of the Cave mindset, believing that this is the world.

However, in the description that you have provided, they would have been placed here after an understanding of social structure and daily function. Even if they did not kill themselves, I believe that even the strongest people would develop psychological disorders. An example of this would be like the movie Cast Away, where Tom Hanks has conversations with the Wilson Volleyball. They may hallucinate, have delusions, and could potentially even develop Dissociative Identity Disorder.

Another theory would be that this human may potentially lose the will to live. They may not even have ideas of killing themselves, but would eventually wither and cease to live through a lack of humanity. The brain is a powerful thing, and as mentioned before, social interaction is imperative to human survival.

What you describe is actually in use today, although not for use of punishment. Sensory deprivation tanks are used for relaxation, although studies have found that even short periods of time can produce hallucinations in individuals, equally across those who are prone to hallucinations and those who are not. I hope this answered your questions about the effects your tank would have on an individual.


I would say until they sucessfully commit suicide, through refusal to eat or drink, due to the psycohlogical torture. It sounds rather horrific.

But given they do not go insane and all of their physical needs are taken care or, water, air, food, waste removal etc... then potentially as long as most other humans, potentially longer than average as they may be less likely to encounter pathogens, and be run over by a car or other accident.

I think the answers to this question support my point on insanity: How long can a human stand to be underground?


Rapid onset of insanity - hallucinations at least

A complete lack of stimulus (such as you're talking about here) fairly readily causes hallucinations. This is the Ganzfeld effect and here's a good ten-minute YouTube video where some dudes try it out and report utterly fantastic results.

This, in like half an hour. I don't know what would happen to someone subject to these conditions indefinitely; I'm not a mental health professional. But if hallucinations set in in less than an hour, I am pretty sure the victim of this torture (because it is torture) would be a complete mess after (say) a year.


Until they die of natural causes (such as a strong disease or old age).

In other words, their life expectancy does not change, since they have all they need.

I am unsure as to whether the likelihood of infection increases, due to the cramped, moist environment, or whether it decreases, due to limited contact with the outside world and a semi-sterile environment.

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    $\begingroup$ I am not sure "they live until they die" can be taken as an answer... $\endgroup$
    – L.Dutch
    Commented Jun 14, 2019 at 15:50
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    $\begingroup$ I think the answer is correct, and shows that the box is not a factor in life expectancy. $\endgroup$
    – cmm
    Commented Jun 14, 2019 at 19:42
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    $\begingroup$ I think this might be a bit more helpful if you explained how you came to this conclusion. . . $\endgroup$
    – HDE 226868
    Commented Jun 14, 2019 at 22:10

Life expectancy is reduced drastically. If the person doesn't commit suicide (as covered in other answers), they'd develop dementia rather rapidly because of the lack of stimuli. I'd wager they wouldn't survive longer than 2 years, but that's speculation.

Our mammal brains are rather complicated things that we don't understand entirely, but there's consensus among scientists that it needs training like a muscle to maintain it's full functionality. By putting someone into a box like that, you remove most of the stimuli that could keep the brain in working order for any amount of time.

  • Senses: You remove almost all input from the eyes and ears, making them extremely sensitive, maybe to the point where the prisoner wouldn't be able to look through the binoculars at the world anymore. You also remove the sense of touch because there's no person to touch the prisoner and the box would soon feel as farmiliar as their own body (Our brains react different to our own touches versus a different person's touch. That's why you cannot tickle yourself.) Depending on the died you remove the sense of taste and smell as well.
  • Social interactions: We might not be aware of it, but the countless unwritten rules of society take up a large portion of out brain power. The struggle of many autistic people to learn all those rules is an indicator of that. By removing direct social contact to people, you shut down another large part of the brain.
  • Creating new memories: Have you ever remembered that mindlessly boring day 2 weeks ago? No? So wouldn't your prisoner. The lack of stimuli would impede their ability to create new memories of their imprisonment. Maybe what little they can see of the outside world would become a substitude for personal experiences, but our brains have a tendency to remember things that happened to ourselves better than things that happened to other people.
  • Recalling memories and knowledge: If the prisoner has no use at all for any memories (because there's literally nothing they can do with them), they'll forget all of them. How to do math, how to read and write, what the names of their friends were and how to speak. The only things they would remember are things they actively use within the box like how to use cutlery (if provided), how to use the toilet (if provided) and maybe some memories they obsess about during their imprisonment. Everything else fades with time.

What's left after all that? An empty shell that lost all brain power but the very basics of survival. Since the brain consumes much of our energy, the unnecessary brain cells will be killed and recycled. That's the definition of dementia.

Changes in eating frequently occur. Caregivers of people with late-stage dementia often provide pureed diets, thickened liquids, and assistance in eating, to prolong their lives, to cause them to gain weight, to reduce the risk of choking, and to make feeding the person easier.[36] The person's appetite may decline to the point that the person does not want to eat at all. They may not want to get out of bed, or may need complete assistance doing so. Commonly, the person no longer recognizes familiar people. They may have significant changes in sleeping habits or have trouble sleeping at all. (Wikipedia)

Lack of hygiene may leed to infections. Lack of appetite may leed to malnurishment. Lack of thirst may leed to strokes or kidney failures. In the end, even though the box provides everything the prisoner needs to survive, they will die prematurely because their impaired brains are unable to utilize these facilities.


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