Science, Tech, Math › Science How Long You Can Live Without Food, Water, or Sleep Share Flipboard Email Print Science Biology Anatomy Basics Cell Biology Genetics Organisms Physiology Botany Ecology Chemistry Physics Geology Astronomy Weather & Climate By Anne Marie Helmenstine, Ph.D. Chemistry Expert Ph.D., Biomedical Sciences, University of Tennessee at Knoxville B.A., Physics and Mathematics, Hastings College Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. She has taught science courses at the high school, college, and graduate levels. our editorial process Facebook Facebook Twitter Twitter Anne Marie Helmenstine, Ph.D. Updated August 08, 2019 You can live without air conditioning and indoor plumbing, but there are some true necessities of life. You can't survive for long without food, water, sleep, or air. Survival experts apply the "rule of threes" to lasting without essentials. You can go about three weeks without food, three days without water, three hours without shelter, and three minutes without air. However, the "rules" are more like general guidelines. Obviously, you can last a lot longer outside when it's warm than when it's freezing. Similarly, you can last longer without water when it's humid and cool than when it's hot and dry. Take a look at what ultimately kills you when you go without the basics of life and how long people have survived without food, water, sleep, or air. How Long Does Starvation Take? JGI/Jamie Grill / Getty Images The technical name for starvation is inanition. It is extreme malnutrition and calorie deficiency. How long it takes for a person to starve to death depends on factors that include general health, age, and starting body fat reserves. One medical study estimated the average adults could last from 8 to 12 week without food. There are documented cases of a few individuals lasting 25 weeks without food. A starving person is less sensitive to thirst, so sometimes death is from the effects of dehydration. The weakened immune system also makes an individual more likely to catch a fatal infection. Vitamin deficiency may also lead to death. If a person lasts long enough, the body starts using protein from muscles (including the heart) as an energy source. Usually, the cause of death is cardiac arrest from tissue damage and electrolyte imbalance. As a side note, starving people don't always get inflated stomachs. Stomach distension is a form of malnutrition from severe protein deficiency called kwashiorkor. It can occur even with sufficient caloric intake. The belly is filled with fluid or edema, not gas, as is commonly thought. Dying of Thirst MECKY / Getty Images Water is an essential molecule for life. Depending on your age, gender, and weight, you consist of around 50 to 65% water, which is used to digest food, carry oxygen and nutrients through the bloodstream, remove wastes, and cushion organs. Since water is so critical, it should come as no surprise that dying from dehydration is an unpleasant way to go. Oh, in the end, a victim is unconscious, so the actual dying part isn't so bad, but that only occurs after days of pain and misery. First comes thirst. You'll start to feel thirsty after losing about two percent of your body weight. Before unconsciousness occurs, the kidneys start to shut down. There isn't enough fluid to produce urine, so most people stop feeling the need to urinate. Attempting to do so anyway can result in a burning sensation in the bladder and urethra. Lack of water causes cracked skin and a dry, raspy cough. Coughing won't be the worst, though. While you might be out of fluids, that won't prevent vomiting. The increased acidity of the stomach can produce dry heaves. Blood thickens, increasing heart rate. Another unpleasant result of dehydration is a swollen tongue. While your tongue swells, your eyes and brain shrink. As the brain shrinks, the membrane or meninges pulls away from the bones of the skull, potentially tearing. Expect a horrible headache. Dehydration eventually leads to hallucinations, seizures, and a coma. Death can result from liver failure, kidney failure, or cardiac arrest. While you might die of thirst after three days without water, there are numerous reports of people lasting a week or longer. Several factors come into play, including weight, health, how much you exert yourself, temperature, and humidity. The record is supposedly 18 days, for a prisoner accidentally left in a holding cell. However, it's reported he may have licked condensation from the walls of his prison, which bought him some time. How Long Can You Go Without Sleep? Squaredpixels/Getty Images Any new parent can verify it's possible to go days without sleeping. Yet, it's an essential process. While scientists are still unraveling the mysteries of sleep, it's known to play roles in memory formation, tissue repair, and hormone synthesis. Lack of sleep (called agrypnia) leads to decreased concentration and reaction time, diminished mental processes, reduced motivation, and altered perception. How long can you go without sleep? Anecdotal reports indicate soldiers in battle have been known to stay awake for four days, and that manic patients have lasted three to four days. Experiments have documented normal people staying awake for 8 to 10 days, without any apparent permanent damage after a night or two of normal sleep to recover. The world record holder was Randy Gardner, a 17-year-old high school student who stayed awake for 264 hours (around 11 days) for a science fair project in 1965. While he was technically awake at the conclusion of the project, he was completely dysfunctional by the end. However, there are rare disorders, such as Morvan's syndrome, which can cause a person to go without sleep for several months! The question of how long people can stay awake ultimately remains unanswered. Suffocation or Anoxia Hailshadow/iStock How long a person can go without air is really a question of how long he can go without oxygen. It's further complicated if other gases are present. For example, breathing the same air over and over is more likely to be lethal because of the excess carbon dioxide rather than the depleted oxygen. Death from removing all oxygen (like a vacuum) may occur from the results of the pressure change or possibly temperature change. When the brain is deprived of oxygen, death occurs because there is insufficient chemical energy or glucose to feed brain cells. How long this takes depends on temperature (colder is better), metabolic rate (slower is better), and other factors. In cardiac arrest, the clock starts ticking when the heart stops. When a person is deprived of oxygen, the brain can survive for about six minutes after the heart stops beating. If cardiopulmonary resuscitation (CPR) starts within six minutes of cardiac arrest, it's possible for the brain to survive without significant permanent damage. If oxygen deprivation occurs some other way, perhaps from drowning, for example, a person loses consciousness between 30 and 180 seconds. At the 60-second mark (one minute) brain cells start to die. After three minutes, lasting damage is likely. Brain death typically occurs between five and ten minutes, possibly fifteen minutes. People can train themselves to make more efficient use of oxygen. The world record holder for free diving held his breath for 22 minutes and 22 seconds without suffering brain damage! References Bernhard, Virginia (2011). A Tale of Two Colonies: What Really Happened in Virginia and Bermuda?. University of Missouri Press. p. 112. "The Physiology and Treatment of Starvation". US National Library of Medicine.