Eachnight may earn commissions for products you purchase through our links. Our articles and reviews include affiliate links and advertisements, including amerisleep advertising. Learn more Updated September 16, 2021Just about everyone has gone 24 hours without sleep for one reason or another, so you probably know that feeling of brain fog you get after you’ve been up all night. But sleep deprivation can have way worse consequences than that, ranging from cognitive decline and irritability to upping your risk for a serious accident. Not to mention the dangerous health impacts long-term sleep deprivation can have on just about every system in your body.If you suffer a severe bout of sleep deprivation, whether it’s due to acute insomnia or environmental factors, you’ll start feeling the impacts pretty quickly. Below, we’ll talk about the different symptoms you might experience based on how many hours you’ve been awake.24 Hours AwakeJust about everyone on Earth has been up for 24 hours. Maybe you pulled an all-nighter studying for a test. Maybe you work the night shift. Maybe you caught a long-haul redeye and didn’t get any sleep on it. Whatever the reason, you probably know the effects of staying awake for 24 hours quite well. They include:DrowsinessAnxietyImpaired focusIrritabilityOvereating/increased appetiteReduced hand-eye coordinationExcessive daytime sleepinessA stray 24 hours of lost sleep won’t do any permanent damage to your health, and its effects normally go away after a good night’s rest. However, according to the CDC, a full day without sleep can put you at increased risk of car accidents. So if you’ve gone that long without rest, you might want to avoid driving or operating heavy machinery.36 Hours AwakeAfter 36 hours of lack of sleep, you’ll start to have more severe symptoms. Your urge to sleep will grow stronger, and you may experience microsleeps—falling asleep unexpectedly for a period of around 30 seconds to a minute—and all the symptoms you had after 24 sleepless hours will intensify. In addition, you might experience new symptoms like:Lowered reaction timeImpaired alertnessInability to make decisionsAltered behaviorReduced memoryCravings for junk foodExtreme fatigueLowered immunity48 Hours AwakeTwo solid days awake will start to seriously impair every part of your mental and physical functioning. Most people don’t make it two days awake without experiencing some sleep, even if it is just microsleeps. You’ll feel an overwhelming, nearly irresistible urge to sleep. All the symptoms you experienced in your first two days awake will start to snowball, and you might even begin to hallucinate. You could also suffer increased anxiety and stress, extreme mood swings, and severe exhaustion.72 Hours AwakeWhen you hit 72 hours up, you probably won’t be able to remain awake on your own. You could fall asleep anywhere: at your desk, in the bathroom, at the lunch table, or behind the wheel. You probably also won’t be able to think straight, to the point even your ability to converse may be impaired. Your emotions will swing wildly, which could lead to anything from a depressed mood to anxiety to paranoia or even mania.You might also find basic social interactions more difficult. Delirium may set in, and you could become disoriented, confused about the time or date, unaware of your surroundings, or catatonic. By this point, you might start having hallucinations. These hallucinations will almost always be visual, and they could be as simple as thinking you saw something out of the corner of your eye that wasn’t there, but they could also become much more severe and complex.96+ Hours AwakeIf you go 4 days or more without any sleep, it will start to seriously disrupt your connection to reality and your ability to function at the most fundamental level. You may find it hard to do the most basic things like read, spell, and talk. At this point, you’re in significant danger of having an accident doing the simplest tasks. Get some sleep if you can. And if you can’t, see a doctor right away.Chronic Sleep DeprivationMost of the time, “sleep deprivation” doesn’t just mean suffering 3 or 4 straight days of 0 sleep—the majority of people have chronic sleep deprivation, meaning they habitually get several fewer hours of sleep than they need for months or years at a time.Americans as a whole are notoriously sleep-deprived. Over 1 in 3 of us don’t get enough sleep. This could be caused by anything from stress to overwork to staying up too late binge-watching TV. Even teenagers suffer chronic sleep deprivation—mostly due to their increased sleep needs and the fact that their natural sleep schedule is often a lot later than school start times.In general, most people need around 8 hours of sleep per 24 hours. This sleep need can vary by plus or minus an hour, but almost every adult on the planet needs between 7 and 9 hours total sleep time, period.Kids need even more. Newborns and infants should spend anywhere from 12 to 15 hours a day sleeping. Toddlers need 11 to 13, school kids 9 to 11, and even teens still need up to 10. Your need for sleep won’t drop off to around 8 hours a night until your late teens or early 20s.If you’re not hitting this minimum, you should either make sleep more of a priority or see a doctor for insomnia treatment.At a certain point though, sleep expert Alicia Roth, PhD, DBSM says, “Your body will eventually shut itself down and go to sleep. It’s incredibly rare for people to go more than a couple of days with absolutely no sleep, even though we may not have perceived sleeping.”FAQsCan you die of sleep deprivation?Most of the time, your homeostatic sleep drive will take over before you’re in danger of just dropping dead. It’s very difficult to keep yourself awake long enough to actually die of sleep deprivation.However, it is possible to keep up moderate sleep deprivation in which you only get 4 or 5 hours a night for years and even decades. Long-term sleep deprivation like this can up your risk for conditions that can easily be fatal, like cardiovascular disease, heart attack, stroke, high blood pressure, obesity, and diabetes, as well as mental problems like depression and generalized anxiety.There’s one disease, however, where insomnia is the thing that kills you rather than causing something else fatal. That disease is called fatal familial insomnia (FFI). In this rare illness, a mutation of the PRNP gene leads to failure in thalamus function and eventual total lack of ability to sleep, which leads to death, often within a year or 2 of symptom onset.Don’t worry though; this disease is incredibly rare. There are only about 70 families known to scientific literature to have FFI.Is my bed disrupting my sleep?Maybe. It’s no secret an uncomfortable bed can make it harder to fall asleep or disrupt your sleep during the night. If your mattress sags, it can cause pain that keeps you awake. If it’s too firm, the pressure can distract you and prevent you from falling asleep. If it’s too bouncy, your partner can wake you up moving around at night. Whatever the problem with your mattress, if it’s keeping you up, it’s time to spring for a new one.What can I do about insomnia?Practicing good sleep hygiene is the best insomnia prevention method. Sleep hygiene simply means maintaining healthy sleep habits on a nightly basis. Don’t stare at screens for about an hour before bed. Keep the TV and laptop out of the bedroom. Make sure your bedroom is cool to aid your body as it lowers its core temperature for sleeping. Always go to bed at the same time every night. Keep your bedroom as dark as possible with blackout curtains.Also get at least 150 minutes of moderate to intense exercise every week to keep your system primed for regular sleep. Always avoid caffeine and other stimulants after lunch, since caffeine stays in your bloodstream for many hours after you drink it.If even solid sleep hygiene practices don’t help you catch some Zs, Cognitive Behavioral Therapy —or retraining your brain for better sleep—might be the next step.Why do we sleep?Nobody really knows. We know sleep is necessary for survival, and lack of it can impact everything from your cardiovascular system to your nervous system to your immune system. But as far as why that’s true, it’s still mostly a mystery.Theories abound as to what sleep does for our brains and bodies, and it seems to do a lot more than just help us recharge after a day’s work. Some scientists believe REM sleep is how our brains categorize and sort the events and information of the day.Many also believe sleep is essential for flushing out harmful waste products created by normal neurological processes, which cerebrospinal fluid may do overnight. This may be why sleep deprivation causes cognitive impairment, but more research is needed for any solid conclusions.What causes insomnia?Lots of different things can cause you to miss shuteye. Stress and anxiety are big factors since these feelings can lead to racing thoughts and a more active nervous system at night, making it difficult to quiet down enough to go to sleep.Traveling to different time zones can also throw off your circadian rhythm—the body’s internal clock—and disrupt your sleep for up to a week or two until the jetlag wears off. Shift work can also cause a kind of social jetlag by interrupting your circadian rhythm.Poor sleep habits like too much napping, sleeping in on the weekends, or using screens before bed can also mess up your sleep. If you find yourself consistently failing to fall or stay asleep, it may be time to see a doctor to rule out any sleep disorders like sleep apnea, insomnia, or problems with your sleep cycle.Bottom LineSleep is vital to pretty much every aspect of your health, and nothing is stronger evidence of that than how rapidly your health can decline after a few nights without rest. So it’s important to prioritize a good night’s sleep and see a sleep specialist or have a sleep study if you can’t get one.About the author Kiera PritchardKiera Pritchard’s curiosity around dreams and dreaming sparked her passion for sleep science. In addition to freelancing for eachnight, Kiera is also a physical trainer and strives to help others lead healthy lives while asleep and awake. Since joining our team, Kiera has compiled multiple sleep health guides offering our readers advice on how to improve their days and evenings. Find more articles by Kiera CommentsLeave a comment Kimberly A Edgehouse May 10, 2021 at 8:40 am ReplyI am interested in your nap study. I am 61 soon and I would like to participate. Leave a comment Cancel replyLeave a CommentYour email address will not be published. Required fields are marked * Comment Name Email I agree to the Terms and Conditions of this website.