The Limits Of Sleep Deprivation: How Long Can You Go?

Sleep is essential for our physical, mental, and emotional health. But how long can we go without it?

The longest anyone has gone without sleep is 11 days, or 264 hours. However, it's unclear exactly how long humans can survive without sleep. After just one night of no sleep, you can start to feel the effects, with symptoms like daytime sleepiness, anxiety, and irritability. As the hours without sleep accumulate, the effects of sleep deprivation become more severe, with hallucinations often occurring after 48 hours without sleep. After 72 hours, a person may begin to slur their speech or walk unsteadily, and may experience a rapid and severe decline in mental health.

After 24 hours without sleep, you may experience symptoms like trouble concentrating, impaired judgment, and diminished memory

Sleep is essential for our bodies to function properly. After 24 hours without sleep, you may experience symptoms such as trouble concentrating, impaired judgment, and diminished memory. These symptoms can negatively impact your daily life and ability to perform tasks. Here are some detailed explanations of these symptoms:

Trouble Concentrating

Concentration is crucial for carrying out daily tasks and maintaining focus. However, after 24 hours without sleep, you may find it challenging to concentrate on any given task. This can manifest as difficulty thinking clearly, an inability to make decisions, or a tendency to make careless mistakes. You may also struggle with your memory, both in the short term and long term.

Impaired Judgment

Sleep deprivation can affect your judgment, making it harder for you to assess your level of impairment. Similar to the effects of alcohol, a lack of sleep can impair your performance and reaction time. This can be dangerous, especially when operating vehicles or heavy machinery, as your reaction time slows down significantly.

Diminished Memory

Sleep plays a vital role in memory consolidation and recall. When you don't get enough sleep, your brain struggles to absorb and retrieve new information effectively. This can impact your ability to learn and remember things, whether it's fact-based knowledge, episodic memories, or procedural memories like riding a bike. Sleep deprivation can also lead to long-term memory issues and potentially contribute to conditions like Alzheimer's disease.

It's important to prioritize sleep to maintain optimal cognitive function and overall well-being. While the immediate effects of sleep deprivation may be temporary, prolonged sleep deprivation can have more severe consequences on your health and daily life.

After 36 hours without sleep, you may experience increased mood changes, alterations in brain function, and physical symptoms like tremors

After 36 hours without sleep, the effects of sleep deprivation become increasingly severe. You may experience increased mood changes, such as feelings of apathy and euphoria, and alterations in brain function, such as reduced concentration and an impaired ability to think creatively. You may also notice physical symptoms like tremors and muscle tension, and you might begin to hallucinate.

At this stage of sleep deprivation, your body is under considerable stress. Your sleep-wake cycle helps regulate the release of hormones like cortisol, insulin, and human growth hormone. Going without sleep for an extended period can, therefore, alter several bodily functions and throw everything off kilter, from hormone imbalances to a slowed metabolism. All the side effects of sleep deprivation you may have experienced up to this point will intensify, and you can expect to experience fluctuations in your mood, attention, body temperature, and appetite.

After 36 hours without sleep, you might also begin to experience illusions, which are a misinterpretation of something that's real. For example, you might see a sign and think it's a person. You might also find it difficult to properly perceive the length of time that has passed.

The longer you go without sleep, the more severe the effects will become. After 48 hours without sleep, you will likely experience microsleep, which is a protective reflex from your brain. During microsleep, you will fall asleep for a brief moment, perhaps up to 30 seconds, and you may wake up feeling confused or disoriented. By 72 hours without sleep, you will have an overwhelming urge to sleep, and your ability to regulate your emotions will be severely compromised. You may feel irritable, anxious, and depressed, and you may start to experience complex hallucinations and delusions.

After 48 hours without sleep, you may experience symptoms of depersonalization and derealization, or problems with accurately perceiving yourself and reality

Sleep deprivation can have serious effects on the body and mind, and it doesn't take long for these to set in. After 48 hours without sleep, the body and mind will be experiencing some severe symptoms.

After 48 hours without sleep, an individual is likely to experience microsleep. Microsleep is a reflexive response from the brain, forcing a person to fall asleep for a brief moment. These episodes can last up to 30 seconds, and the person experiencing them may be completely unaware that they happened. Alternatively, they may wake up feeling disoriented and confused. This phenomenon is dangerous, especially if it occurs while performing an activity that requires concentration, such as driving.

In addition to microsleep, other severe symptoms can occur after 48 hours without sleep. The body's immune system is disrupted, with inflammatory markers, which usually help to prevent and target illnesses, circulating at higher levels. Natural killer (NK) cell activity, which responds to immediate health threats like viruses or bacteria, decreases.

At this stage of sleep deprivation, an individual's ability to regulate their emotions and accurately perceive the world around them is severely compromised. They may experience symptoms such as irritability, anxiety, depression, paranoia, and hallucinations. They may also struggle with executive functioning and thinking.

Sleep deprivation can also lead to dissociative symptoms, including depersonalization and derealization. A study on the effects of sleep deprivation on dissociation found that sleep restriction led to a decrease in vigour and activity levels, while fatigue levels increased. The study also found a significant increase in dissociative levels, with individuals experiencing feelings of detachment from reality.

It is important to note that the effects of short-term sleep deprivation should go away once an individual catches up on sleep. However, chronic sleep deprivation can have more serious and long-lasting impacts on health.

After 72 hours without sleep, you may experience a rapid and severe decline in mental health, including symptoms of psychosis and detachment from reality

At this point, you will likely experience an overwhelming urge to sleep, and your ability to stay awake on your own will be limited. Your ability to think clearly, especially when it comes to executive functions such as multitasking, remembering details, and paying attention, will be significantly impaired. Your emotions may also be affected, with increased irritability, anxiety, and depression being common symptoms.

In addition to the cognitive and emotional effects, your perception of reality may become distorted. Hallucinations, both complex and simple, are likely to occur. Hallucinations are when you see, hear, or feel something that is not actually there. For example, you may see lights or objects that aren't really present, or hear voices that aren't there. These hallucinations may be simple at first but will become more complex as time goes on.

Along with hallucinations, you may experience illusions, which is when you misinterpret something that is actually there. For example, you may see a sign and think it is a person, or you may struggle to interpret the emotions of others.

The combination of hallucinations and illusions can lead to a state of acute psychosis, where you perceive reality very differently from those around you. You may develop delusions, which are firm beliefs that you hold even when there is evidence to the contrary. For example, you may become convinced that you are a famous actor being followed by paparazzi. Your speech and behavior may also become disorganized, and you may act in ways that are unusual or unexpected.

The good news is that, in most cases, sleep deprivation psychosis is not permanent. Getting enough sleep can usually resolve the symptoms, although the amount of time needed to recover will depend on how long you have gone without sleep. It is recommended that you get at least 7 hours of sleep per day as an adult to maintain good mental and physical health.

The effects of short-term sleep deprivation usually go away after getting some rest, but chronic sleep deprivation can have long-term health complications

Sleep is a vital part of our physical, cognitive, and mental well-being. It is crucial in maintaining our physical, mental, and emotional health. Even after just one night of no sleep, you can start to feel the effects. The longer you go without sleep, the more intense these effects will be.

Short-term sleep deprivation

After 24 hours without sleep, you may experience symptoms such as trouble concentrating, impaired judgment and decision-making, diminished memory and attention, impaired vision, hearing, and hand-eye coordination, tremors, and increased muscle tension. These symptoms are similar to the effects of intoxication, with research suggesting that staying awake for 24 hours can affect your cognitive performance as much as having a blood alcohol content of 0.10%, which is above the legal limit for driving in most places.

After 36 hours without sleep, the effects of sleep deprivation intensify, and you may experience increased stress, hormonal imbalances, slowed metabolism, mood fluctuations, attention and appetite changes, and intensified side effects from the previous day.

By 48 hours without sleep, it is likely that you will experience microsleep, which is when your brain forces you to fall asleep for a brief moment, up to 30 seconds. You may also experience symptoms such as increased sleepiness and fatigue, challenges with time perception, reduced concentration and creativity, illusions, and simple visual hallucinations.

Chronic sleep deprivation

Chronic sleep deprivation, or repeatedly not getting enough sleep, can have long-term health complications. It can increase your risk of high blood pressure, certain cancers such as colorectal cancer, cognitive impairment, dementia, poor balance and coordination, weakened immune system, impaired glucose tolerance and Type 2 diabetes, overweight and obesity, and depression and other mood disorders.

The effects of short-term sleep deprivation usually go away after getting some rest, but chronic sleep deprivation can lead to more severe and long-lasting health issues.

Frequently asked questions