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How many days can humans go without sleep? The 17-year-old who stayed awake for about 11 days

とある研究者｜身近な疑問を本気で調べる

Have you ever experienced feeling groggy the day after pulling an all-nighter, finding it difficult to think about even simple things?

I have.

Even just one night is pretty tough, isn't it...?

However, in the past, there was a person who was medically observed to have stayed awake for about 11 days, or 264 hours.

11 days.

That means they didn't sleep even after 11 nights had passed.

Honestly, I thought my limit was about 3 days at most. When I saw the number 11, I suspected that there must have been some different conditions involved.

Can humans really go that long without sleep?

And if it was possible to stay awake for about 11 days, is that the human limit?

This time, based on a famous case reported in the 1960s and sleep research, I investigated how many days humans can go without sleep.

Note: This article deals with cases where healthy people choose to stay awake. Insomnia and fatal familial insomnia, a hereditary prion disease, are not included in the records of limits because their causes are different from those of a healthy person pulling an all-nighter.

The answer first: There is an 11-day case. But the limit is unknown.

Let me start with the conclusion.

There is a case that was medically observed where someone stayed awake for about 11 days.
However, the limit to how long a human can go without sleeping at all is unknown.

The subject of this case was Randy Gardner, who was 17 at the time.

The time recorded in the medical report was 264 hours. In days, that is exactly about 11 days.

When you lay it out like this, you can see how long 264 hours really is. It is the length of pulling an all-nighter for a full day, repeated 10 more times.

However, there is something to be careful about here.

264 hours is not a number that measures the human limit.

"There is a case of someone staying awake for about 11 days" and "humans can stay awake for a maximum of 11 days" are completely different stories.

A 17-year-old who stayed awake for about 11 days

This event took place between the end of 1963 and the beginning of 1964.

As a high school science project, Randy Gardner challenged himself to see how long he could stay awake with the help of his friends. Later on, sleep researcher William Dement and others joined in to observe.

Subsequently, Gardner's condition and the brain waves during his recovery sleep were reported in a medical paper.

The paper noted that during the 264 hours of sleep deprivation, various behavioral changes commonly seen with lack of sleep appeared. On the other hand, it was also reported that he did not reach a state that the authors called 'sleep deprivation psychosis'.

In other words, it is not as simple as the claim sometimes seen online that,

if you don't sleep for 11 days, you will completely lose your sanity

is not the case.

Of course, this does not mean that there were 'no major problems.' With prolonged sleep deprivation, various functions required for staying awake and active—such as concentration, memory, mood, perception, speech, and calculation—begin to break down.

However, this chart is not a timetable that says 'this symptom will definitely appear after X hours.' This is because there are significant individual differences in vulnerability to sleep deprivation.

Even if people go without sleep for the same amount of time, the way it affects them is not the same for everyone.

So, is '11 days' the human limit?

If one person was able to stay awake for about 11 days, is the human limit around 11 days?

Unfortunately, we cannot say that.

There are three main reasons for this.

1. A single case cannot determine the limits of humanity

There are individual differences in reactions to sleep deprivation.

If age, physical constitution, health condition, and surrounding environment differ, the effects will vary even if people stay awake for the same amount of time.

Just because one 17-year-old stayed awake for 264 hours does not mean it can be applied to everyone.

2. It does not mean that the 'limit was reached' at 264 hours

Gardner ended his challenge at 264 hours.

However, he did not stop because his body could no longer stay awake at that exact moment.

In other words, 264 hours was the time reached, not the time confirmed as the absolute limit beyond which it is impossible.

3. Experiments pushing to the limit cannot be conducted

So, if we observe healthy people until they truly cannot stay awake anymore, can we determine the limit?

In theory, one would like to think so.

However, we cannot continue experiments that lead to serious health damage or accidents until death or loss of consciousness occurs.

Therefore, data confirming the "absolute limit in days" for humans cannot be obtained.

The conclusion so far is clear.

264 hours is a confirmed long-duration case. It is not the maximum time a human can endure.

In the first place, can "not sleeping at all" be proven?

While researching, this was what concerned me the most.

Is a person who appears awake from the outside really not sleeping for even a single second?

Actually, when sleep deprivation becomes severe, very short periods of sleep lasting a few seconds can occur regardless of the person's will.

This is microsleep.

In some cases, the person may not realize they have fallen into a microsleep. Furthermore, their eyes may be open, and they may even appear to be awake at first glance.

The body appears to be awake.

But the brain is not processing information coming in from the outside.

...Such a state can occur.

We need to distinguish this carefully.

It cannot be definitively stated that Randy Gardner experienced microsleeps.

The issue is that the entire 264-hour period was not continuously measured using methods like EEG as is done today.

Even with people watching, it is impossible to detect every few seconds of sleep. Therefore, it is difficult to strictly prove that he 'did not sleep for even a single moment.'

At first, it was a simple question of 'how many days can one endure?'

However, as I investigated, I arrived at the question ofwhat it actually means to be 'fully awake' in the first place.that.

What is truly familiar and scary is not an 11-day all-nighter.

Having read this far,

I don't pull all-nighters for 11 days, so this doesn't apply to me,

some of you may have thought.

I also initially thought this was a story about a very unique record.

But when I looked into sleep research, I found that everyday sleep deprivation was actually more relevant to everyone.

Van Dongen et al. divided healthy adults into conditions of 4, 6, and 8 hours of time in bed per day and examined their cognitive task performance over 14 days. In another experiment, they also compared this to up to 3 days of total sleep deprivation.

As a result, in the 4-hour or 6-hour conditions, cognitive function declined cumulatively day by day.

The conclusion of the entire study is thatcontinuing to limit sleep to 6 hours or less per day can result in a decline in cognitive function equivalent to up to two full nights of sleep deprivation.it is stated.

What is even more concerning is the sleepiness the individual feels.

Although subjective sleepiness increased initially, subsequent increases were relatively small and did not clearly distinguish between the 4-hour and 6-hour conditions. On the other hand, objective task performance continued to deteriorate.

In other words,

even if you get used to the feeling of sleep deprivation, it does not necessarily mean your brain function has returned to normal.

that is.

It is not necessarily true that 'as long as you don't pull an all-nighter, you'll be fine.'

Even a small amount of sleep deprivation each day can accumulate without you noticing.

If you don't sleep, will you die?

At this point, there is one more question that comes to mind.

Will humans die if they don't sleep?

To put it simply,it is not known on which day a healthy person would die from sleep deprivation alone.

This is because it is impossible to conduct an experiment where a person is kept awake until they die.

The results of animal experiments cannot be directly applied to the number of days for humans. Furthermore, 'fatal familial insomnia' is not just a sleep issue; it is a progressive disease caused by the accumulation of abnormal prion proteins in the brain. It must be considered separately from a healthy person pulling an all-nighter.

However, 'not knowing the number of days until death' does not mean that it is safe up to that point.

Sleep deprivation affects attention, judgment, and reaction long before you reach your limit. Especially while driving, microsleeps can lead to serious accidents even if they last only a few seconds.

Before you even approach a limit with an unknown answer, real dangers have already begun.

Please absolutely do not try this.

The 264 hours introduced this time is not a goal to strive for.

  • Do not attempt to break records for staying awake for long periods.

  • Do not drive a car or ride a bicycle while feeling strong sleepiness.

  • Do not assume that your abilities have fully returned just because caffeine has masked your sleepiness.

  • Do not push yourself if you experience confusion, sensory abnormalities, or severe physical discomfort.

  • Consult a medical institution if insomnia persists and interferes with your daily life.

Microsleeps cannot be prevented by willpower alone, and the person may not even realize they are happening.

Do not use the feeling that 'I can still stay awake' as proof of safety.

Final Answer: How many days can a human go without sleep?

There is a famous medically observed case of someone staying awake for about 264 hours, or approximately 11 days.

However, this is not the absolute limit for humans.

This challenge did not end because the limit was reached. Furthermore, one single case cannot determine the limit for all of humanity.

Additionally, with prolonged sleep deprivation, "microsleeps"—seconds-long periods of sleep that the person may not even notice—can occur.

Therefore, it is difficult to completely prove that someone did not sleep for even a single moment during a long-term challenge.

Thus, the answer at this moment is,

A case of someone staying awake for about 11 days has been confirmed. However, the limit to how long a human can go without sleeping at all is unknown.

is what it would be.

And what is truly relevant to us is not an 11-day all-nighter.

Even just a little bit of sleep deprivation every day can cause your attention and judgment to decline more than you might think.

If you were to tell someone just one thing, try saying this:

There is a case of a human staying awake for about 11 days.
However, that is not the human limit, and it is also difficult to prove that they did not sleep at all.

The brain is not something we can keep awake indefinitely just by our own will.

Next time: What temperature of heat can humans withstand?

In parts 1 through 3, we have explored human limits through breath-holding and sleep.

Now, let's look at the "limit of heat," which is relevant in the summer.

We live our lives outdoors even on sweltering days when the temperature exceeds 35°C.

On the other hand, in a sauna, we sometimes enter spaces that exceed 80°C.

So, what temperature of heat can humans actually withstand?

When we looked into it, we found that the heat a human can withstand is not determined by air temperature alone.

The burden on the body changes significantly depending on humidity, wind, sunlight, and duration of exposure.

And a figure often cited as the limit for humans is the "wet-bulb temperature of 35°C".

Next time, using research data as a guide, we will seriously investigate:

  • What temperature of heat can humans withstand?

  • Why is humidity, not just air temperature, important?

  • Is a "wet-bulb temperature of 35°C" truly the human limit?

we will seriously investigate these questions.

If you have any other questions that would be interesting to investigate seriously, please let us know in the comments.

Your question might become the next research topic.

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