What Happens When You Don’t Sleep for a Day?


What is Sleep Deprivation?

What Long-Term Risks Come with Sleep Deprivation?

Chronic Health Conditions

Weight Gain

Expedited Aging

Diminished Performance

Can Sleep Deprivation Kill You?

What Happens After 24 Hours Without Sleep?

What’s the Longest Anybody’s Gone Without Sleep?

What About Losing a Little Sleep Every Night?

How Can I Improve My Sleeping Habits?

Are You Ready to Improve Your Sleeping Habits?

Everybody knows you need sleep to lead a happy, healthy life. According to the Centers for Disease Control and Prevention, otherwise known as the CDC, adults should get at least 7 to 9 hours of sleep every night. But what happens if your body isn’t getting the rest it needs?

The CDC estimates 1 in 3 adults are getting less than 7 hours of rest each night. Meaning, approximately 30% of our population is sleep deprived. While postponing sleep may leave time for other tasks, there are severe risks of skipping out on shut-eye altogether.

In this article, we discuss what sleep deprivation is, how it impacts your physical and mental health, and finally, what you can expect after 24 sleepless hours. Let’s dive in.

What is Sleep Deprivation?

As the name implies, sleep deprivation occurs when you’re not getting the sleep you need. Habitually getting less than 7 to 9 hours of rest each night can result in chronic sleep deprivation, impacting all areas of your life.

College students, new parents, and busy employees are all too familiar with the practice of pushing off sleep to get more done. And while that may seem like a good idea at the moment, nobody can go without sleep— even if you’d like to think you can.

If you’re lacking sleep, the unpleasant side effects of sleep deprivation will catch up to you at some point. However, sleep deprivation impacts everybody in different ways. Some of the more common short-term symptoms include:

  • Daytime fatigue and sleepiness
  • Difficulty concentrating
  • Poor memory
  • Weakened immune system
  • Mood swings and irritability
  • Increased appetite
  • Diminished coordination and decision-making skills

When you sleep, your body has a chance to refresh and restore itself after a day of stressors. Depriving yourself of the opportunity to rest after a demanding day is never a good idea.

What Long-Term Risks Come with Sleep Deprivation?

Everybody knows that just one night of inadequate sleep can leave you feeling tired and cranky the next day. However, not everybody understands the risks of regularly going without rest.

Chronic Health Conditions

Sleepless nights can have a more significant impact on your overall health than you may think. Long-term sleep deprivation can lead to several health issues, including:

  • Stroke
  • Heart disease
  • Obesity
  • Depression
  • Anxiety
  • Diabetes

Going without sleep also makes it harder to lose weight, causes you to age faster, and increases the difficulty of standard daily tasks such as driving. Let’s talk about that a bit more.

Weight Gain

When you’re not following a normal sleep-wake routine, your internal processes are thrown off; this involves everything from hormone production to digestive functions. When your body needs rest, it responds by over-producing cortisol, a stress hormone.

Increased cortisol exposure can lead to a greater accumulation of abdominal fat, creating what some doctors call a “stress belly.” Excess fat around your abdomen puts you at higher risk of heart disease and diabetes (as we mentioned above).

A lack of sleep also makes you hungrier. When your body is sleep-deprived, it produces more of the hunger hormone, ghrelin, and less of the appetite-suppressing hormone, leptin. Usually, those needing sleep have cravings for sugar, as it’s quick and simple energy.

If you’re tired, you may feel less inclined to fight your sugar cravings and choose something healthier. Over time, this can lead to dietary problems and weight gain. One recent study uncovered a direct link between lack of sleep and increased BMI.

Expedited Aging

As superficial as it may seem, one of the tell-tale signs of sleep deprivation is your appearance. When you see somebody with noticeable bags under puffy eyes and droopy eyelids, you can usually assume they need some sleep.

In a recent study, researchers had participants view 20 headshots and rate them based on fatigue and mood. Across the board, participants described the photos of sleep-deprived subjects as appearing sad. During this study, participants noted the well-rested subjects were more approachable and attractive.

Beyond under-eye bags, a lack of sleep can cause wrinkles, fine lines, uneven pigmentation, and saggy skin.

When you don’t get enough sleep at night, it weakens your skin’s ability to repair itself; this speeds up the aging process and results in a decreased ability to recover after sun exposure, too.

Diminished Performance

Not getting enough sleep undermines all other efforts to perform your best during your day-to-day. Whether you’ve got a big test or a meeting ahead, skipping sleep to prepare leaves you no better off than if you were to get some sleep instead.

You’re almost always better choosing sleep over additional preparation because your brain at rest consolidates memories, stores new information, improves your attention span, refreshes your energy levels, and readies you to tackle difficult tasks.

Beyond the “big” events of the next day, cutting your sleep short influences your overall functionality. When you’re tired, you’re not as sharp, your decision-making skills aren’t on par, and your coordination is off-kilter.

According to the CDC, 1 in 25 adults has nodded off behind the wheel in the last 30 days.  In 2015, the U.S. Police reported 90,000 car crashes involving sleep-deprived drivers. And in 2017, the National Highway Traffic Safety Administration reported 795 deaths as a result of drowsy driving.

The scariest part? You’re usually unaware of your impairment, meaning you typically feel like you’re perfectly fine to jump behind the wheel or take that big exam. Your brain is so tired you don’t notice just how exhausted you really are. Even if you don’t feel tired after countless waking hours, your body still needs sleep.

Can Sleep Deprivation Kill You?

Simply put, yes. Forcing yourself to stay awake and abstain from sleep will eventually kill you. In 2012, a man died after attempting to watch every single game in the European Championship and going a total of 11 days without sleep.

How long it can take to pass away, and the exact cause of death may vary from person to person, though. While some individuals take a week or two to pass away, others may perish sooner or later down the line.

When your body is without sleep, it is in a stressed state— your immune system is suppressed, making you more susceptible to illness; you produce more stress hormone cortisol; your blood pressure rises; and your internal temperature drops.

Some people may die because their internal temperature drops so low that they succumb to hypothermia. Meanwhile, others might die as a result of bacteria or illness, since their immune systems are unable to fight off germs.

For a slew of moral and ethical reasons, researchers do not hold sleep deprivation studies on humans any longer than 2 or 3 days. However, on studies involving rats, they found rats can survive for 32 days without sleep before dying. The cause of death amongst rats varied, as discussed above.

Everybody is different, and while going days without sleep isn’t healthy for anyone, the time it takes sleeplessness to turn fatal changes from person to person. For that reason, organizations such as Guinness Book of World Records do not even acknowledge submissions for voluntary sleep deprivation— as it’s a lot more dangerous than people may think.

What Happens After 24 Hours Without Sleep?

Most people have pulled an all-nighter at some point or another. While you likely don’t look back upon that sleepless night as a “fun” time, you may not realize what you were putting your body through.

After 24 hours without sleep, you’re cognitively impaired. In fact, at just 17 hours without sleep, your judgment, memory, and hand-eye coordination skills are all suffering. At this point, irritability has likely set in. Beyond feeling tired and groggy, you’re more tense, more emotional, your pain receptors are very sensitive, and believe it or not, your hearing is impaired, too.

Your body responds to this lack of sleep by producing more stress hormones and ceasing glucose metabolism to keep you alert and fueled. By now, your brain has probably entered a state of “local sleep.”

During local sleep, parts of your brain shut down and sleep in waves; while some regions and neurons in your brain are resting, others are active. Local sleep helps your mind recharge in-between the times your body has the chance to rest fully.

When local sleep isn’t enough, your brain begins to shut down in trance-like microsleeps. Microsleeps generally last 15 to 30 seconds, but they come in unnoticeable spells. Microsleeping is like zoning out— you’re completely unaware when it’s happening, and once you zone back in, you’ve realized your brain was just blank for however long you were staring off into space.

Microsleeps occur when your brain can no longer prevent sleep. Local sleep was its attempt to restore itself without real rest, but your mind can only stay active for so long. Once it can no longer keep going, it succumbs and microsleeps.

If your brain shuts down and microsleeps while you’re behind the wheel, it can be dangerous, and possibly deadly to not only yourself but others as well.

What’s the Longest Anybody’s Gone Without Sleep?

Back in 1964, high-schooler Randy Gardner set the world record for the longest a human has gone without sleep— staying awake for 11 days and 25 minutes. In an attempt to win a science fair, Randy Gardner and his two classmates allowed researchers to study the impact sleeplessness can have on the human body.

After only a few days into their wake-a-thon, William Dement, a sleep researcher from Stanford University, heard about the boy’s experiment through the local newspaper and hopped on board. Much to Gardner’s parent’s relief, Dement was available to monitor and observe Randy’s behavior through the duration of the study.

But that wasn’t enough. Gardner’s parents also recruited Lt. Cmdr. John J. Ross of the U.S. Navy Medical Neuropsychiatric Research Unit to monitor their son’s health. For the next days, Dement, Ross and Randy’s two classmates helped keep him awake, observed his behaviors, and kept tabs on his declining cognitive abilities.

During the experiment, Randy’s behavior fluctuated. For example, on day ten, he was reported beating Dement at a game of pinball. However, back on day four, Randy had an episode in which he believed he was a professional football player. When his classmates, Ross, and Dement tried to convince him otherwise, Randy lashed out and accused them of being racist.

The most common cognitive and behavioral changes reported were slurred and slow speech, hallucinations, paranoia, and poor concentration. On day four, Gardner mistook a street sign for a person. Then, on day eleven, when asked to subtract from seven repeatedly starting with 100, he stopped at 65. When Ross asked him why he stopped, Gardner told him he’d forgotten what he was supposed to be doing.

Gardner acted as you might suspect any person would over the course of days without sleep— he was moody, disoriented, irrational, and all-around impaired. But once the clock struck 2 a.m. on January 8, 1964, Randy Gardner had successfully beat the record for time without sleep. He then was whisked away to a naval hospital so researchers could monitor his brain activity as he recovered.

In interviews today, Gardner reflects on his sleepless stint as “crazy” and says going without sleep felt like having early Alzheimers, where he couldn’t remember anything. But he recovered like a champ and was back in high school two days later.

What About Losing a Little Sleep Every Night?

Most people don’t go a full 24-hours without sleep. However, that doesn’t mean people are getting the recommended amount of hours each night. What happens if you are only sleeping 3, 4, or 5 hours a night? Is a week of inadequate sleep equal to the same amount of sleep deprivation? Can you “make it up” on the weekend?

As mentioned above, sleep deprivation isn’t just going a night without sleep. Sleep deprivation is getting less than the recommended 7-9 hours each night. Doing this habitually leads to significant issues, such as weight gain, moodiness, decreased performance, and more.

Some people claim they can lose sleep during the week and make it up on the weekend. While it’s still up to a lot of debate, the science seems against it.

The most straightforward and simple solution: work to make sleep a priority and get a good 7-9 hours each night.

How Can I Improve My Sleeping Habits?

  • Go to bed and wake up at the same time every day. Reinforce your natural sleep cycle by going to bed and waking up at the same time every day, even on weekends!
  • Eat sleep-promoting foods around dinnertime. Heavy, greasy foods during the evening hours can hinder a good night’s rest. Instead, choose whole grains and fatty fish for dinner to get sound sleep.
  • Keep your bedroom conducive to sleep. Your bedroom should be an oasis for sleep with cool temperatures, dark blinds, and a comfortable mattress. Reserve your bedroom for sleep and sleep alone, and it’ll strengthen your brain’s association that bedtime equals sleep time.
  • Exercise for 30 minutes a day, three times a week. Exercise contributes to a healthy lifestyle, but did you know it helps you get restful sleep, too? Thirty minutes of physical activity has been shown to improve sleep efficiency and promote deeper sleep cycles.
  • Limit blue-light exposure in evening hours. Blue light is the biggest detractor from a good night’s rest. Blue light impedes melatonin production, the hormone influencing your sleep-wake cycle. To facilitate melatonin production and fall asleep at a reasonable hour, put the phone or any technology emitting blue light away in the hour or two leading up to bedtime.
  • Find outlets for stress. Stress can make it hard to fall asleep, and not getting enough sleep can leave you feeling anxious. Finding healthy ways to deal with the worries of the day prevents you from entering a vicious cycle of stressed out, sleepless nights.
  • Invest in a new, comfy mattress. If you’re trying to sleep on an old, lumpy bed, or merely a mattress that’s incompatible with your sleep style, it can be hard to drift off. Buying a comfortable bed for your needs is an easy way to kickstart better sleep.
  • Develop a routine and stick to it. Your body desires routine, and sticking to a steady sleep-wake schedule keeps all systems in check. Once you’re accustomed to falling asleep and waking up at a particular time every day, it becomes second nature and your sleep troubles are left in the past.

Are You Ready to Improve Your Sleeping Habits?

While sleep may be low on our priority list, it’s crucial to leading a healthy life. Skipping sleep to make time for more work or extra social activities may seem more advantageous to you at the moment, but at the end of the day, sacrificing sleep impacts your mental, physical, and overall health.

As a society, we are sleep deprived; so much so that losing only one hour of sleep when Daylight Saving Time rolls around increases our drowsy driving accident rates by 7%. The National Commission on Sleep Disorders Research reports sleep-related accidents and disorders which impact work productivity cost the American economy between $100 and $150 billion annually.

Sleep deprivation kills, and our failure to recognize the impact of a sleepless night continues to baffle researchers— as humans are the only mammal that actively puts off rest.

We hope this article has given you a greater insight into what happens when you’re entering your 24th hour without sleep. To get better rest and improve your bedtime habits, we recommend sticking to a fixed schedule and improving time management skills to ensure you’re always getting a full eight hours.

Interested in learning more about data-driven fatigue management?

or download our free eBook on the Science of Sleep for industrial workforces

About the author

Meg Riley is a Certified Sleep Science Coach and writer/editor for Sleep Junkie. After graduating from Penn State University, Meg began writing about the mattress industry and the science behind getting a good night’s sleep.


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