How Long Can You Go Without Sleep?

Like food and water, sleep is a fundamental human requirement. It has even been said that one could survive for three times as long without food as one could without sleep. However, most people will experience sleep deprivation at some point in their life due to the new babies, studying, worrying about an important meeting or business deal, etc. 

Although occasional lack of sleep may not seem like a big deal, the effects of sleep deprivation can manifest themselves in various shapes and negatively impact your health and in some extreme cases even lead to death

How Much Sleep Do You Really Need?

According to various researches, adults should get between 7 to 9 hours of sleep each night. However, providing the right answer to the question how much sleep do you really need is not so easy as everyone is different. So, the amount of sleep you need per night can vary based on your own individual needs

Like we have already mentioned in one of our previous articles, you will know if you are getting enough sleep by evaluating how you feel as you go about your day. Therefore, if you are getting enough sleep, you will feel energetic from the moment you get up to the moment you go to bed again.

You should also see how productive and happy you are on the amount of sleep you are getting, whether you have certain health issues such as being overweight, or if you are at risk for some disease. 

Think about whether you have problems falling asleep or staying asleep all night or if you are too dependent on caffeine to get you through the day. Think also about your age as age can determine the amount of sleep that you need. It is known that newborns and infants need a lot more sleep than adults. 

Gender may also play a role in how much sleep you need and various studies showed that women tend to sleep a bit longer than men although the reasons for this are still unknown. All this can help you figure out the perfect number of sleep hours that will work for you.

Sleep quality is important as well, and if you are concerned about how much sleep you are getting, you should visit a doctor and try to find an appropriate solution for your problem,

How Long Can You Go Without Sleep?

Humans can go without sleep for about 11 days. But, how do we know this?

The answer lies in a research conducted in 1965 when a 17-year-old Randy Gardner set a world record by staying awake for 264 hours (11 consecutive days).

He and other research subjects were carefully monitored. Although none of them experienced serious medical, neurological, and psychological problems, all of them showed significant problems with concentration, perception, motivation, and higher mental processes.

It is still not clear exactly how long we can survive without sleep. We only know that the effects of sleep deprivation don’t take long before they start to appear. 

After 3-4 nights without sleep, you will start to hallucinate while prolonged sleep deprivation can lead to various cognitive impairments, delusions, irritability, paranoia, and psychosis. 

Although dying from sleep deprivation in this way is rare, it can happen. 

What Are the Effects of Sleep Deprivation on Our Health?

The negative effects of sleep deprivation have been observed in countless studies and it has been proved that chronic poor sleep increases the risks for serious medical conditions, such as heart disease, obesity, and diabetes

During sleep, our bodies produce certain hormones that help control appetite, glucose processing, and metabolism. Poor sleep can lead to the increased production of cortisol, which is also known as the stress hormone.

In addition, less insulin is released and this, combined with the increased cortisol, may lead to too much glucose in your bloodstream which further increases the risk for type 2 diabetes. 

Read on and find out what you can expect after 24 hours and more without sleep.

What To Expect after 24 Hours Without Sleep?

Missing 24 hours of sleep isn’t unusual and we often miss sleep because of work, studying, taking care of the newborn child, etc. Although this can affect you, It won’t have a significant impact on your overall health.

According to a study published in the International Journal of Occupational Medicine and Environmental Health, the consequences of 24-hour sleep deprivation can be compared to the cognitive impairment of someone with a blood alcohol concentration of 0.10, which is above the legit limit to drive in most states. 

It affects your judgement and memory, makes decision-making difficult and causes a decline in eye-hand coordination. It also makes you more emotional, decreases your attention, impairs your hearing, and increases the risk of death from a fatal accident. 

Other effects include:

  • irritability
  • altered perception
  • increased muscle tension
  • tremors

Symptoms of 24-hour sleep deprivation disappear once you get a normal amount of sleep and make up for the lost hours.

36 Hours Without Sleep

Staying awake for just 36 hours can have more serious effects on your body and your overall health. As we mentioned, your sleep helps regulate the release of certain hormones, and going without sleep for an extended period of time can affect this and alter other bodily functions as well.

Increased levels of inflammatory markers will appear in your blood, which can lead to high blood pressure and cardiovascular disease. In addition, as your hormones will be affected, you will be more emotional than usually.

You will feel extreme fatigue and the same effects as though you are dehydrated. Your motivation will be low, your appetite will be affected as well as metabolism. It can also cause the changes in your body temperature and levels of stress, mood changes, etc. 

Some other effects include:

  • difficulty making clear decisions
  • inability to reason properly
  • decreased attention
  • impaired speech, such as poor word choice and intonation

48 Hours Without Sleep

After two nights without sleep most people have difficulty staying awake. Your body will begin to compensate for the lost sleep by shutting down for periods of light sleep known as microsleeps.

These episodes can last up to 30 seconds. They happen involuntarily and the person experiencing them is not consciously aware that they are occurring. These episodes are followed by a period of confusion and disorientation. 

Staying awake for this long disrupts your immune system and those inflammatory markers that we mentioned, which help your body prevent illnesses, start to circulate at increased levels while the activity of the natural killer cells slows down (these are the cells responsible for responding to immediate threats to your health, such as viruses and bacteria).

72 Hours Without Sleep

After 72 hours without sleep you will feel an overwhelming urge to sleep and you may not be able to stay awake on your own. Three days without sleep will cause significant deficits in concentration, motivation and perception. It will affect your ability to think and remember details and make it difficult to complete even simple tasks.

Your emotions will also be affected and you may be easily irritated. You may experience anxiety, a depressed mood or even paranoia. Research has also found that such sleep deprivation makes it more difficult to process the emotions of other people so you can’t recognize angry or happy facial expressions.

Finally, you may also experience illusions and hallucinations and see things that are not really there.

What If Sleep Deprivation Becomes Chronic?

Chronic sleep deprivation is when you don’t get enough sleep on a regular basis. It is different than missing sleep for a night or two in a row and it is also more common. 

The Centers for Disease Control and Prevention report that almost 35% of American adults don’t get enough sleep each night. Chronic sleep deprivation can significantly affect your health, performance and safety. 

There are many causes of chronic sleep deprivation such as the stresses of your daily life, medical or mental-health conditions that disrupt your sleep, and it can often occur due to the unrecognized sleep disorders such as insomnia, restless legs syndrome, sleep apnea, sleep walking, night terrors, etc.

Not getting enough sleep over a short period of time may cause:

  • drowsiness
  • anxiety
  • frequent mood changes
  • forgetfulness
  • difficulty staying alert
  • difficulty concentrating
  • decreased performance at work or school
  • cognitive impairments
  • increased risk of illness or injury 

In the long term, not getting enough sleep can affect your immune system and increase the risk of certain health conditions such as high blood pressure, heart disease and stroke, obesity, diabetes, and mental illnesses. 

Fatal Familial Insomnia

Fatal Familial Insomnia is a rare, genetically inherited prion disease. It can occur spontaneously, which is known as sporadic fatal insomnia and one needs to inherit at least one copy of the specific protein mutation to develop this condition. 

Once someone begins to show the symptoms of Fatal Familial Insomnia, which start with insomnia, the disease progresses quickly and other symptoms emerge as well such as lack of appetite, weight loss, hallucinations, and dementia.

Death usually occurs within 12-18 months after the first symptoms appear.

The best-known case of Fatal Familial Insomnia is that of Michael Corke. He died after 6 months of total sleep deprivation. But, it is difficult to determine whether lack of sleep is the definitive cause of death in people with FFI based only on the experiments on animals. So we can’t say for sure whether 6 months is exactly how much you can go without any sleep before you die. 

So, How Long Can You Go Without Sleep?

The answer is we don’t really know. It isn’t clear how long humans can survive without sleep, but it is clear that first serious symptoms appear after only 36 hours of sleep deprivation.

Staying awake for a night or two once in a while probably won’t do much harm to your overall health. However, if you often skip sleep or if you can’t sleep for some other reason, you should talk to your doctor who will get to the root of your symptoms and help you establish a normal sleep schedule again. 


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