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Sleep Health

How Long Can You Go Without Sleep?

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    Last Updated
    April 4, 2022
    min read

    How long can you go without sleep? The longest time a person has gone without sleep is 264 hours (11 days). This was recorded by the Guinness world records. Set by Randy Gardner in 1965.

    In this fast-paced world, sleep can be hard to come by. Too many of us suffer from impractical schedules, all-night work or study sessions, and unyielding pressure from friends, family, and even ourselves to "hustle and grind" – depriving ourselves of sleep in the process.

    But as common as sleep deprivation has become today, it's something that we have to actively fight against. Sleep deprivation can have serious short-term and long-term health implications. In fact, just lacking a few hours of sleep a day can lead to poor coordination and concentration, as well as higher levels of stress. But that's just the tip of the iceberg.

    Read on to discover exactly what lack of sleep can do to the body, and how long you can go without sleep before you start to feel the negative effects of sleep deprivation.

    The Effects Of Sleep Deprivation On The Body

    Getting enough sleep, especially deep sleep, is important because it helps our bodies rest and repair themselves through the night. As such, not getting enough sleep, or consistently getting poor sleep, can lead to a whole spate of symptoms and medical conditions.

    When you don’t get enough sleep, your body’s 24-hour biological clock, known as the circadian rhythm, goes out of whack. This internal clock is supposed to send signals to your body when it’s time to sleep and when it’s time to be awake.

    But when your circadian rhythm is off, you can feel tired and unwell during the day. You can also have more trouble sleeping, which prevents you from getting the REM sleep that your body needs. Without proper REM sleep, your brain can't go through the same processes it goes through to retain your memories.

    According to sleep experts, there are two main stages of sleep deprivation: acute sleep deprivation and chronic sleep deprivation. Acute sleep deprivation is what you would feel if you went for one or two days without sleep.

    The most common effects of acute sleep deprivation include:


    Naturally, when you go for several hours without sleep, you tend to feel drowsy and fatigued, even during the day. Daytime sleepiness isn't just irritating, but it can also put you at serious risk of getting injured if you're not careful.

    According to one survey, people who got six hours or less of sleep a day were more likely to fall asleep while driving. The NHTSA estimates that 697 people were killed in drowsy driving-related crashes in 2019.

    Increased Stress

    While stress can cause people to have sleepless nights, inadequate sleep can also lead to higher levels of irritability, mood instability, and stress. It's a vicious cycle.

    Impaired Judgment

    One study found that night without sleep can impair performance as much as a blood-alcohol content of 0.10 percent. That number is far beyond the legal limit for driving.

    This is because, just like alcohol, inadequate sleep can affect judgment. Sleep-deprived people are said to have a harder time assessing how impaired their cognitive abilities, hand-eye coordination, and concentration are when they're tired.

    Reduced Concentration And Focus

    Sleep deficiency can lead to lower alertness and poor concentration. Without proper sleep, you'll have a harder time focusing on complicated tasks, especially ones that require logical reasoning.

    Problems With Short Term Memory

    According to the NIH, without sleep, you cannot "form or maintain the pathways in your brain that let you learn and create new memories." Light sleep isn't enough to keep our memories intact – scientists believe that memory consolidation requires both non-REM and REM sleep. You especially need stage 3 non-REM sleep, which is the period of deep sleep that is necessary for you to feel alert and refreshed the next day.

    How Long Can You Go Without Sleep?

    24 hours.

    Research shows that the negative effects of sleep deprivation don’t often take longer than 24 hours to occur, except in some rare medical cases, like the 27-year old man who went months at a time without sleep.

    What Happens To The Body Without Sleep For 24 Hours

    After just 24 hours without sleep, you’ll start to notice a lag in cognition. Your memory will falter, your thoughts will become sluggish, and it may be difficult to maintain a single line of thought. Your judgment will be affected, your decision-making will become sloppy, and you’ll likely experience a decline in hand-eye coordination.

    What Happens To The Body Without Sleep For 36 Hours

    After 36 hours of sleep, it's not just your cognition and mental health that suffers – so does your heart. With this much time spent not sleeping, you're likely to experience an increase in blood pressure. Your heart rate will also rise above your usual average.

    You may also start to experience changes in your appetite, temperature, and metabolism. This is because your sleep-wake cycle is linked to the release of hormones that control certain bodily functions.

    What Happens To The Body Without Sleep For 48 Hours

    After 48 hours of no sleep, you will experience high levels of stress. Your white blood cells will reduce dramatically, and your body will not be able to fight off potential threats. This means you'll be prone to all sorts of infections and diseases.

    What Happens To The Body Without Sleep For 72 Hours

    After just a few days without sleep, your mind can begin to conjure up all kinds of hallucinations, which can also become a dangerous side effect to staying awake. Research shows that hallucinations often occur after about 72 hours without sleep.

    What Are The Effects Of Chronic Sleep Deprivation?

    While you usually can recover from acute sleep deprivation by sleeping well the following night, chronic sleep deprivation can be much more problematic. Chronic sleep deprivation occurs when you don’t get enough sleep over a long period of time and end up incurring something called sleep debt.

    Sleep debt is described as the difference between how much sleep your body needs and how much you really get. With fewer hours of sleep in you than necessary, you have a sleep debt. People with more sleep debt are said to be at higher risk for:

    • Heart disease and strokes;
    • Diabetes;
    • Weight gain and even obesity;
    • Weaker immune system;
    • Higher blood pressure;
    • Mental diseases such as dementia and Alzheimer’s disease;
    • More physical pain.

    How Much Sleep Do You Actually Need?

    According to the CDC, most adults need anywhere between seven to nine hours of sleep a night.

    And if you know you're not getting enough sleep, here's how you can fix your sleep schedule:

    • Practice good sleep hygiene.
    • Avoid screens at least an hour before bed.
    • Eat an early dinner.
    • Keep your room's temperature cool.
    • Get regular exercise.
    • Find a good pillow and mattress to keep you comfortable.

    Frequently Asked Questions About Sleep Deprivation

    Will your body eventually force you to sleep?

    Yes, your body can force you to sleep if you haven’t slept in a long while.

    Can you die from no sleep?

    As it currently stands today, there is no known human death that was directly caused by a lack of sleep. There were, however, several rats that died in a sleep-deprivation experiment in the lab of Allan Rechtschaffen, a researcher at the University of Chicago.

    How long can you go without sleep before hallucinating?

    Scientists believe it can take 72 hours of sleep deprivation before you start to experience hallucinations.


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