How Long Can You Go Without Sleep? Function, Hallucination, and More

How long can you go?

The longest recorded time without sleep is 453 hours and 40 minutes. Although it’s unclear exactly how long humans can survive without sleep, it isn’t long before the effects of sleep deprivation start to show. In 1997, Guinness World Records stopped monitoring this category due to serious health risks associated with sleep deprivation.

After only 3 or four nights without sleep, you can start to hallucinate. Prolonged sleep deprivation can lead to:

• cognitive (thinking) impairments
• irritability
• delusions
• paranoia
• psychosis

Although dying from sleep deprivation is extremely rare, it can happen.

Read on to find out how staying awake for a full 24 hours or more can affect your body, and how much sleep you actually need to function.

What to expect after 24 hours without sleep

Missing 24 hours of sleep isn’t uncommon. You might miss a night of sleep to work, cram for a test, or take care of a sick child. While it might be unpleasant to stay up all night, not to mention having to manage the consequences of the next day, your overall health is unlikely to be significantly affected.

Still, missing a night of sleep does affect you. Studies have compared 24-hour wakefulness to having a blood alcohol concentration of 0.10%. This is above the legal limit to drive in most states.

Some effects of going 24 hours without sleep include:

• drowsiness
• irritability
• impaired decision making
• impaired judgement
• altered perception
• memory deficits
• vision and hearing impairments
• decreased hand-eye coordination
• increased muscle tension
• tremors
• increased risk of accidents or near misses

Symptoms of 24-hour sleep deprivation usually go away once you’ve had some shut-eye.

What to expect after 36 hours without sleep

Staying awake for 36 hours can have intense effects on your body.

Your sleep-wake cycle helps regulate the release of certain hormones, including cortisol, insulin, and human growth hormone. As a result, going without sleep for an extended period like this can alter several bodily functions.

This includes your:

• appetite
• metabolism
• temperature
• mood
• stress level

Some effects of going 36 hours without sleep include:

• extreme fatigue
• hormonal imbalances
• decreased motivation
• decision making that could lead to harmful consequences
• inflexible reasoning
• decreased attention
• speech impairments, such as issues with word choice and intonation

What to expect after 48 hours without sleep

After 2 nights of missed sleep, problems, including difficulty completing tasks that demand a high attention level, mood shifts, depression, and increased feelings of tension, arise.

Sleep-deprived people might experience periods of light sleep that can last up to 30 seconds. During these “microsleeps,” the brain is in a sleep-like state. Microsleeps happen involuntarily. After a microsleep, you might feel confused or disoriented.

Staying awake for 48 hours also disrupts the immune system. Inflammatory markers, which help your body prevent and target illnesses, start to circulate at increased levels. Some research has shown that natural killer (NK) cell activity decreases with sleep deprivation. NK cells are white blood cells that respond to immediate threats to your health, such as viruses or bacteria.

What to expect after 72 hours without sleep

After 72 hours without sleep, most people experience an overwhelming urge to sleep. Many are unable to stay awake on their own.

Going 3 days without sleep profoundly limits the ability to think clearly, while executive functions, such as multitasking, remembering details, and paying attention, become challenging. This level of sleep deprivation can make it difficult to see even simple tasks through to completion.

Emotions are also affected. People who have undergone this level of sleep deprivation may be easily irritated. They may experience a depressed mood, anxiety, or paranoia. Research has also found that sleep deprivation makes it more difficult to process others’ emotions. In studies, participants with 30 hours of sleep deprivation had difficulty recognizing angry and happy facial expressions. A 2017 research paper confirmed previous findings.

Finally, several days of sleep deprivation can significantly alter perception. You might experience hallucinations, which occur when you see something that isn’t there. Illusions, which are a misinterpretation of something that’s real, are also common. An example is seeing a sign and mistaking it for a person.

Can food and water intake have any effect on this?

Sleep deprivation can change both your appetite and the types of foods you crave. Studies suggest that sleep deprivation is associated with both an increased appetite and an increased desire for foods associated with weight gain. However, consuming empty calories can ultimately leave you more tired.

Eating well may offset some of the effects of sleep deprivation, but only to an extent. Since your body is conserving energy, opt for lean, protein-rich foods, such as nuts and nut butters, cottage cheese, or tofu, if you are having trouble getting sufficient sleep. Avoid fatty proteins, such as steak or cheese, as these will make you sleepier.

Dehydration can worsen the effects of sleep deprivation — such as grogginess and difficulty concentrating — so it’s also important to drink plenty of water.

What if sleep deprivation becomes chronic?

Chronic partial sleep deprivation refers to when you don’t get enough sleep on a regular basis. It’s different than pulling an all-nighter once in a while. It’s also more common than missing 1 or 2 nights of sleep in a row, as most people are likely to sleep for at least a few hours per night.

The Centers for Disease Control and Prevention (CDC) reports that about one-third of American adults don’t get enough sleep per night. Chronic partial sleep deprivation is associated with both short-term health risks and long-term complications.

Not getting enough sleep over a short period, such as a week, may cause:

• anxiety
• unstable mood
• drowsiness
• forgetfulness
• difficulty concentrating
• difficulty staying alert
• cognitive impairments
• decreased performance at work or school
• increased risk of illness or injury

In the long term, not getting enough sleep can reduce immune functioning and increase your risk of certain health conditions. These include:

• high blood pressure
• heart disease
• stroke
• obesity
• type 2 diabetes
• mental illness

How much sleep do you really need?

The amount of sleep you need per night varies according to your age. Generally, newborns and infants require more sleep, while adults need less.

The CDC has issued daily sleep recommendations based on age group:

Gender may also play a role in how much sleep you need. Studies have found that women tend to sleep slightly longer than men, although the reasons for this are unclear.

Sleep quality is also important. If you’re concerned about how much sleep you’re getting, make an appointment with your doctor.

The takeaway

Extreme symptoms, including a reduced ability to think, decision making issues, and speech impairment, resulting from lack of sleep, can begin in as little as 36 hours.

An occasional all-nighter probably won’t cause lasting harm, but if it’s happening regularly — whether by choice or circumstance — it’s worth checking in with a healthcare professional. They can help you stay healthy when sleepless nights are unavoidable or work with you to get your sleep schedule back on track.

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