How Long Can You Function Without Sleep? Effects of Sleep Deprivation

We are all well aware of the importance of getting enough sleep. However, with the stressful lives that most of us live today, sleep is often relegated to the background in favor of completing other work. This is especially true if we are on a timeline. Getting an adequate amount of sleep is not only necessary for our physical well-being, but also for our mental and emotional health. Sleep deprivation can cause all sorts of short-term and long-term health effects and lifestyle diseases. Sleep is a basic bodily function and the body refreshes itself as we sleep. An interesting question that many people often wonder about is just how long can a person continue to function without sleep. Well, read on to find out about how long you can function without sleep.

The longest time ever recorded for a person to go without sleep is around 266 hours or 11 days straight, according to factual data. While there is really no clear information about exactly how much time it is possible for human beings to survive without sleep, what is known, though, is that it won’t take long before the side effects of sleep deprivation start to make their presence felt.^(1, 2)

According to the US Centers for Disease Control and Prevention (CDC), adults between the ages of 18 to 60 years should be getting at least seven to eight hours of sleep every night. However, at the same time, it also estimates that nearly 35 percent of adults in the United States alone do not get a sufficient amount of sleep.^(3,4) As per the sleep recommendations of the CDC, adults should remain awake for no more than 17 hours. People may start experiencing the negative effects of sleep deprivation within 24 hours of not sleeping. So how long can a person really go without sleeping?

Well, sleep requirements vary from person to person, and also depend on the person’s age. For instance, infants and children need nearly twice the amount of sleep than adults.^(5,6) Still, the exact amount of time that a person can survive without sleeping remains unclear. According to a review carried out in 2010, the current world record for an individual going without sleep is 266 hours, just a little over 11 days.⁽¹⁾ Perhaps the most famous experiment that looked at sleep deprivation was carried out in 1964 by a high school student Randy Gardner in California. He managed to go without sleep for 264 hours. However, by the end of the 11 days, Gardner was observed to have become paranoid and he had even begun to hallucinate. Nevertheless, according to his own reports, he recovered without having any type of long-term psychological or physical effects.

Experts have shown that after just three to four nights of no sleep, a person will begin to hallucinate. Sleep deprivation over this can cause many symptoms, including:⁽⁷⁾

• Irritability
• Cognitive impairments
• Delusions
• Psychosis
• Paranoia

While there have not been any reports of a person actually dying from sleep deprivation, but it can happen. So, what happens to the body as you keep crossing each day without sleep Let’s take a look.

In today’s stressful world, going without sleep for 24 hours is not that uncommon. You may end up missing a night’s sleep because you have a big deadline at work the next morning, you need to study for a test, or you have to take care of your sick child. Even though it is not very pleasant to remain awake all through the night, but it is unlikely going to have a very big impact on your overall health. Nevertheless, missing even one night of sleep does have an impact. Studies have shown that staying awake for 24 hours is comparable to having a blood alcohol concentration of 0.10 percent.⁽⁸⁾ It is interesting to note that this amount is above the legal limit permissible for driving in most states in the US.

Some of the effects of not sleeping for 24 hours include:

• Drowsiness
• Impaired judgment
• Irritability
• Mood swings
• Impaired decision making
• Altered perception
• Memory deficits
• Hearing and visual impairments
• Reduced hand-eye coordination
• Tremors
• Increased muscle tension

The adverse effects caused by 24-hour sleep deprivation tend to usually disappear after you catch up on some sleep.

When you go without sleep for 36 hours, it starts to have some pretty intense effects on your body. Sleep is necessary for a variety of bodily functions. The sleep-wake cycle of your body is responsible for controlling the release of many hormones including melanin, insulin, human growth hormone, and cortisol among others. Due to this, if you go without sleep for a long period of time, such as 36 hours, it can bring about a change in many of your bodily functions, including:^(9,10)

• Appetite
• Mood
• Temperature
• Metabolism
• Stress levels

Some of the side effects you may experience after going 36 hours without sleep may include:^(11,12,13)

• Reduced levels of motivation
• Extreme fatigue
• Hormonal imbalances
• Higher likelihood of making risky or rash decisions
• Inflexible sense of reasoning
• Speech impairments, including poor intonation and word choice
• Reduced attention span

After missing two consecutive nights of sleep, most people will find it difficult to remain awake. They are likely to experience periods of falling into a light sleep that can be as short as 30 seconds. These are known as microsleeps, and during this state, the brain goes into a sleep-like state. A sleep-deprived person has no control over these microsleeps and they happen involuntarily. After a bout of microsleep, you are more likely to feel disoriented or confused.^(14,15)

Going without sleep for 48 hours has a profound impact on the immune system. Inflammatory markers of the body, which are responsible for helping the body prevent and also target diseases, begin to move around at an increased rate. Some studies have shown that the activity of natural killer (NK) cell activity reduces with more and more sleep deprivation. NK cells work by responding to any immediate threats to your health, including an attack by bacteria and viruses.^(16,17)

Going for 72 hours of no sleep will cause most people to feel an overwhelming need to sleep, with many being simply unable to remain awake on their own. Going for three days without sleeping will impact your ability to think, especially while carrying out executive functions like remembering details, multitasking, or paying attention. This level of sleep deprivation can even make it challenging to complete simple tasks.⁽¹⁸⁾

After 72 hours of sleep deprivation, emotions also get affected. People who have gone through this type of sleep deprivation often get quickly irritated and are more likely to experience a depressed mood, paranoia, or anxiety. Studies have shown that this level of sleep deprivation makes it much harder to understand other people’s emotions. In one study, in particular, participants who had gone for 30 hours without sleep experienced challenges in recognizing any type of happy and angry facial expressions.^(19,20)

In the end, after many days of sleep deprivation, a person is known to experience significantly altered perception. A person may begin to experience hallucinations, which tend to occur when an individual starts to see things that are not there. Illusions are also common signs. Illusions are known as a misinterpretation of something that is real. For example, seeing a sign and believing it to be a human being.^(21,22)

While it is rare, but sleep deprivation can prove to be fatal in some cases. Sleep deprivation can also kill a person indirectly as it increases the risk of getting into a dangerous accident significantly. According to data from the National Highway Traffic Safety Administration (NHTSA), in 2015, the US police reported 90,000 motor vehicle crashes that happened due to sleep-deprived drivers. The administration also stated that drowsy driving caused 795 deaths in 2017 in the US.⁽²³⁾

At the same time, an extremely rare sleep disorder known as fatal familial insomnia (FFI) can be fatal. FFI is a type of inherited condition that causes a mutation in the prion protein gene, also known as the PRNP gene. This mutated gene causes prions to get misfolded, which then starts accumulating in the thalamus, which is part of the brain that controls sleep in a person. The symptoms of FFI tend to begin in the middle of adulthood and include the following:^(24,25)

• Mild insomnia that starts to get progressively worse
• Lack of appetite
• Weight loss
• Changes in body temperature
• Dementia that starts to progress rather quickly

There is no cure for FFI and if a person is diagnosed with this condition, it is common for them to pass away within 12 to 18 months after experiencing the first symptom.

Sleep deprivation is when a person does not get a sufficient amount of sleep. While it is not really clear as to just how long a person can go without sleep, but during one experiment, a person managed to remain awake for nearly 264 hours. Due to the stressful lives, we all live today, most adults rarely get enough sleep. While missing an hour or two of sleep may not appear to be a big deal, but it can adversely affect your mood, ability to focus, energy levels, and ability to handle challenging tasks. Chronic sleep deprivation can increase the risk of obesity, heart disease, and even diabetes. Most adults need seven to eight hours of sleep every night. Practicing good sleep habits can help you get a better quality of sleep.

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